criyle/codenet-compile-errors huggingface dataset:
Language: C

i;main(){char s[21];for(scanf("%s",s),i=strlen();i--;putchar(s[i]));i=!puts("");}

Compiler output:
main.c:1:1: warning: data definition has no type or storage class
    1 | i;main(){char s[21];for(scanf("%s",s),i=strlen();i--;putchar(s[i]));i=!puts("");}
      | ^
main.c:1:1: error: type defaults to 'int' in declaration of 'i' [-Wimplicit-int]
main.c:1:3: error: return type defaults to 'int' [-Wimplicit-int]
    1 | i;main(){char s[21];for(scanf("%s",s),i=strlen();i--;putchar(s[i]));i=!puts("");}
      |   ^~~~
main.c: In function 'main':
main.c:1:25: error: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
    1 | i;main(){char s[21];for(scanf("%s",s),i=strlen();i--;putchar(s[i]));i=!puts("");}
      |                         ^~~~~
main.c:1:1: note: include '<stdio.h>' or provide a declaration of 'scanf'
  +++ |+#include <stdio.h>
    1 | i;main(){char s[21];for(scanf("%s",s),i=strlen();i--;putchar(s[i]));i=!puts("");}
main.c:1:25: warning: incompatible implicit declaration of built-in function 'scanf' [-Wbuiltin-declaration-mismatch]
    1 | i;main(){char s[21];for(scanf("%s",s),i=strlen();i--;putchar(s[i]));i=!puts("");}
      |                         ^~~~~
main.c:1:25: note: include '<stdio.h>' or provide a declaration of 'scanf'
main.c:1:41: error: implicit declaration of function 'strlen' [-Wimplicit-function-declaration]
    1 | i;main(){char s[21];for(scanf("%s",s),i=strlen();i--;putchar(s[i]));i=!puts("");}
      |                                         ^~~~~~
main.c:1:1: note: include '<string.h>' or provide a declaration of 'strlen'
  +++ |+#include <string.h>
    1 | i;main(){char s[21];for(scanf("%s",s),i=strlen();i--;putchar(s[i]));i=!puts("");}
main.c:1:41: warning: incompatible implicit declaration of built-in function 'strlen' [-Wbuiltin-declaration-mismatch]
    1 | i;main(){char s[21];for(scanf("%s",s),i=strlen();i--;putchar(s[i]));i=!puts("");}
      |                                         ^~~~~~
main.c:1:41: note: include '<string.h>' or provide a declaration of 'strlen'
main.c:1:41: error: too few arguments to function 'strlen'
main.c:1:54: error: implicit declaration of function 'putchar' [-Wimplicit-function-declaration]
    1 | i;main(){char s[21];for(scanf("%s",s),i=strlen();i--;putchar(s[i]));i=!puts("");}
      |                                                      ^~~~~~~
main.c:1:54: note: include '<stdio.h>' or provide a declaration of 'putchar'
main.c:1:72: error: implicit declaration of function 'puts' [-Wimplicit-function-declaration]
    1 | i;main(){char s[21];for(scanf("%s",s),i=strlen();i--;putchar(s[i]));i=!puts("");}
      |                                                                        ^~~~
main.c:1:72: note: include '<stdio.h>' or provide a declaration of 'puts'
Language: C

#include<stdio.h>
#include<stdlib.h>
int main(void){
  char a,b,i,j;
  char rarara[1000];
  char papapa[1000]; 
 gets(rarara);
 for(i=0;rarara[i]!=NULL;i++){};
 a=i;
  for(i=0;i<a;i++)
    papapa[i]=rarara[a-i-1];
  papapa[a]=NULL;
  printf("%s\n",papapa);
  return 0;
}

Compiler output:
main.c: In function 'main':
main.c:7:2: error: implicit declaration of function 'gets'; did you mean 'fgets'? [-Wimplicit-function-declaration]
    7 |  gets(rarara);
      |  ^~~~
      |  fgets
main.c:8:19: warning: comparison between pointer and integer
    8 |  for(i=0;rarara[i]!=NULL;i++){};
      |                   ^~
main.c:12:12: error: assignment to 'char' from 'void *' makes integer from pointer without a cast [-Wint-conversion]
   12 |   papapa[a]=NULL;
      |            ^
Language: C

#include<stdio.h>
#include<string.h>

int main(){
 char in[30];
 fgets(in, 30, stdin);
 for(i = strlen(in) - 2; i >= 0; i--) putchar(in[i]);
 puts("");
 return 0;
}

Compiler output:
main.c: In function 'main':
main.c:7:6: error: 'i' undeclared (first use in this function); did you mean 'in'?
    7 |  for(i = strlen(in) - 2; i >= 0; i--) putchar(in[i]);
      |      ^
      |      in
main.c:7:6: note: each undeclared identifier is reported only once for each function it appears in
Language: C

#include<stdio.h>
int main(void)
{
	char str[20+1];
	int flag = 0;
	int i = 0;
	scanf("%s",str);
	for(i=20;i >= 0;i--)
	{
		if(str[i] == 0x00) 
		{
			flag = 1;
		}
		else if	(flag)
		{		 
			printf("%c", str[i]);
		}
	}
	printf("\n");
	return 0;

Compiler output:
main.c: In function 'main':
main.c:20:9: error: expected declaration or statement at end of input
   20 |         return 0;
      |         ^~~~~~
Language: C

#include<stdio.h>
#include<string.h>

int main(void)
{
	char m[21];
	int f1, s;
	scanf("%s",m);
	s = strlen(m);
	for(f1 = s - 1; f1 >= 0; f1---)
	{
		printf("%c",m[f1]);
	}
	printf("\n");
	return 0;
}

Compiler output:
main.c: In function 'main':
main.c:10:39: error: expected expression before ')' token
   10 |         for(f1 = s - 1; f1 >= 0; f1---)
      |                                       ^
Language: C

#include<stdio.h>
#include<string.h>

int main(void)
{
	char m[21];
	int f1, s;
	scanf("%s",m);
	s = strlen(m);
	for(f1 = s - 1; f1 >= 0; f1--)
	{
		printf("%c",m[f1];
	}
	printf("\n");
	return 0;
}

Compiler output:
main.c: In function 'main':
main.c:12:34: error: expected ')' before ';' token
   12 |                 printf("%c",m[f1];
      |                       ~          ^
      |                                  )
main.c:12:35: error: expected ';' before '}' token
   12 |                 printf("%c",m[f1];
      |                                   ^
      |                                   ;
   13 |         }
      |         ~
Language: C

#include<stdio.h>

int main(){

  char a[21];
  int i=0;
  
  fgets(a,sizeof(a),stdin);
  while(a[i]!='\n')
    i++;
  for(i=i-1;i>=0;i--)
    printf("%c",a[i]);
  printf("\n");
  return 0;

Compiler output:
main.c: In function 'main':
main.c:14:3: error: expected declaration or statement at end of input
   14 |   return 0;
      |   ^~~~~~
Language: C

#include<stdio.h>
#include<string>
int main()
{
	char seq[21];
	int x;
	scanf("%s",&seq);
	x=strlen(seq);
	while(--x>=0)
		printf("%c",seq[x]);
	printf("\n");
}

Compiler output:
main.c:2:9: fatal error: string: No such file or directory
    2 | #include<string>
      |         ^~~~~~~~
compilation terminated.
Language: C

#include<iostream>
#include<string>
using namespace std;

int main()
{
	string str;
	while(cin>>str)
	{
		int i;
		for(i=str.size()-1;i>=0;--i)
			cout<<str[i];
		cout<<endl;
	}

	return 0;
}

Compiler output:
main.c:1:9: fatal error: iostream: No such file or directory
    1 | #include<iostream>
      |         ^~~~~~~~~~
compilation terminated.
Language: C

# include <stdio.h>
# include <string.h>
void main()
{
char str[1024];
gets(str);
int len;
len=strlen(str);
for(int i=len-1;i>=0;i--)
putchar(str[i]);
}

Compiler output:
main.c: In function 'main':
main.c:6:1: error: implicit declaration of function 'gets'; did you mean 'fgets'? [-Wimplicit-function-declaration]
    6 | gets(str);
      | ^~~~
      | fgets
Language: C

#include <stdio.h>
#include <string.h>

int main(void)
{
	char str[21];
	
	scanf("%s", str);
	
	strrev(str);
	
	printf("%s\n", str);
	
	return (0);
}

Compiler output:
main.c: In function 'main':
main.c:10:9: error: implicit declaration of function 'strrev'; did you mean 'strsep'? [-Wimplicit-function-declaration]
   10 |         strrev(str);
      |         ^~~~~~
      |         strsep
Language: C

//
//  main.cpp
//  TestCppCode
//
//  Created by Shahab Uddin on 04/20/13.
//  Copyright (c) 2013 ___Shahab__. All rights reserved.
//

#include <cstdio>
#include <cstring>

int main(int argc, const char * argv[])
{

    char input [20 + 10];

    scanf ("%s", input);

    int length = strlen (input);

    for ( int i = length - 1; i >= 0; i-- ) {
        printf ("%c", input [i]);
    }

    return 0;
}

Compiler output:
main.c:9:10: fatal error: cstdio: No such file or directory
    9 | #include <cstdio>
      |          ^~~~~~~~
compilation terminated.
Language: C

#include<stdio.h>

   int main(void){
          int a[21],b[21];;
          int i =0,j=0;
             while(a[i] != '\0'){
                 scanf("%d",&num[i]);
                    i++;
                   }
                 i--;
               for(; i>=0; i--){
                    b[j] = a[i]
                     j++;
                   }
                     j++;
                b[j]='\0';
                printf("%s\n",b);
              return 0;
           }            
                     
                
               

Compiler output:
main.c: In function 'main':
main.c:7:30: error: 'num' undeclared (first use in this function)
    7 |                  scanf("%d",&num[i]);
      |                              ^~~
main.c:7:30: note: each undeclared identifier is reported only once for each function it appears in
main.c:12:32: error: expected ';' before 'j'
   12 |                     b[j] = a[i]
      |                                ^
      |                                ;
   13 |                      j++;
      |                      ~
Language: C

#include<stdio.h>

   int main(void){
          char a[21],b[21];;
          int i =0,j=0;
             while(a[i] != '\0'){
                 scanf("%d",&num[i]);
                    i++;
                   }
                 i--;
               for(; i>=0; i--){
                    b[j] = a[i];
                     j++;
                   }
                     j++;
                b[j]='\0';
                printf("%s\n",b);
              return 0;
           }            
                     
                
               

Compiler output:
main.c: In function 'main':
main.c:7:30: error: 'num' undeclared (first use in this function)
    7 |                  scanf("%d",&num[i]);
      |                              ^~~
main.c:7:30: note: each undeclared identifier is reported only once for each function it appears in
Language: C

include <stdio.h> 
int main(){
  int a,cnt=0;
  char str[20];
  scanf("%str",str);
  while(str[cnt]!='\0'){
    cnt++;
  }
  for(;cnt>=0;cnt--) printf("%c",str[cnt]);
  printf("\n");
  return 0;
}

Compiler output:
main.c:1:9: error: expected '=', ',', ';', 'asm' or '__attribute__' before '<' token
    1 | include <stdio.h>
      |         ^
Language: C

include <stdio.h> 
int main(){
  int a,cnt=0;
  char str[20];
  scanf("%s",str);
  while(str[cnt]!='\0'){
    cnt++;
  }
  for(;cnt>=0;cnt--) printf("%c",str[cnt]);
  printf("\n");
  return 0;
}

Compiler output:
main.c:1:9: error: expected '=', ',', ';', 'asm' or '__attribute__' before '<' token
    1 | include <stdio.h>
      |         ^
Language: C

#include <stdio.h>
#include <conio.h>

  int main(void){
      char sets[20];
      int i;
      for(i=0; i<20; i++){
       sets[i] = getche();
     }
      for(i=19; i>=0; i--){
       printf("%c",sets[i]);
}
    return 0;
}

Compiler output:
main.c:2:10: fatal error: conio.h: No such file or directory
    2 | #include <conio.h>
      |          ^~~~~~~~~
compilation terminated.
Language: C

#include <stdio.h>

  int main(void){
      char sets[20];
      int i;
      for(i=0; i<20; i++){
       sets[i] = getche();
     }
      for(i=19; i>=0; i--){
       printf("%c",sets[i]);
}
    return 0;
}

Compiler output:
main.c: In function 'main':
main.c:7:18: error: implicit declaration of function 'getche'; did you mean 'getchar'? [-Wimplicit-function-declaration]
    7 |        sets[i] = getche();
      |                  ^~~~~~
      |                  getchar
Language: C

#include <stdio.h>

 int main(void){
    char str[20],strr[20];
    int i;
    scanf("%s",&str);
    for(i=0;str[i]!=\0;i++){
       strr[20-i]=str[i];
    }
    printf("%s\n",strr);
    return 0;
}
    

Compiler output:
main.c: In function 'main':
main.c:7:21: error: stray '\' in program
    7 |     for(i=0;str[i]!=\0;i++){
      |                     ^
Language: C

#include <conio.h>

 int main(void){
    char str[20],strr[20];
    int i,j;
    for(i=0;str[i]!=\0;i++){
       str[i]=getchar();
    }
    j=i;
    for(;j>=0;j--){
    printf("%c",str[j]);
    }
    printf("\n");
    return 0;
}
    

Compiler output:
main.c:1:10: fatal error: conio.h: No such file or directory
    1 | #include <conio.h>
      |          ^~~~~~~~~
compilation terminated.
Language: C

#include <stdio.h>

 int main(void){
    char str[20],strr[20];
    int i,j;
    for(i=0;str[i]!=\0;i++){
       str[i]=getchar();
    }
    j=i;
    for(;j>=0;j--){
    printf("%c",str[j]);
    }
    printf("\n");
    return 0;
}
    

Compiler output:
main.c: In function 'main':
main.c:6:21: error: stray '\' in program
    6 |     for(i=0;str[i]!=\0;i++){
      |                     ^
Language: C

main(){char s[21];gets(s);printf("%s\n",strrev(s));return 0;}

Compiler output:
main.c:1:1: error: return type defaults to 'int' [-Wimplicit-int]
    1 | main(){char s[21];gets(s);printf("%s\n",strrev(s));return 0;}
      | ^~~~
main.c: In function 'main':
main.c:1:19: error: implicit declaration of function 'gets' [-Wimplicit-function-declaration]
    1 | main(){char s[21];gets(s);printf("%s\n",strrev(s));return 0;}
      |                   ^~~~
main.c:1:27: error: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
    1 | main(){char s[21];gets(s);printf("%s\n",strrev(s));return 0;}
      |                           ^~~~~~
main.c:1:1: note: include '<stdio.h>' or provide a declaration of 'printf'
  +++ |+#include <stdio.h>
    1 | main(){char s[21];gets(s);printf("%s\n",strrev(s));return 0;}
main.c:1:27: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
    1 | main(){char s[21];gets(s);printf("%s\n",strrev(s));return 0;}
      |                           ^~~~~~
main.c:1:27: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:1:41: error: implicit declaration of function 'strrev' [-Wimplicit-function-declaration]
    1 | main(){char s[21];gets(s);printf("%s\n",strrev(s));return 0;}
      |                                         ^~~~~~
Language: C

#include <stdio.h>
#include <string.h>

int main(void)
{
	char str[21];
	
	scanf("%s", str);
	
	printf("%s\n",strrev(str));
	
	return (0);
}

Compiler output:
main.c: In function 'main':
main.c:10:23: error: implicit declaration of function 'strrev'; did you mean 'strsep'? [-Wimplicit-function-declaration]
   10 |         printf("%s\n",strrev(str));
      |                       ^~~~~~
      |                       strsep
Language: C

#include <stdio.h>
#include <string.h>

int main(void)
{
	char str[21];
	char str2[21];
	
	scanf("%s", str);
	
	strrev(str);
	strcpy(str2, str);
	
	printf("%s\n", str2);
	
	return (0);
}

Compiler output:
main.c: In function 'main':
main.c:11:9: error: implicit declaration of function 'strrev'; did you mean 'strsep'? [-Wimplicit-function-declaration]
   11 |         strrev(str);
      |         ^~~~~~
      |         strsep
Language: C

#include<stdio.h>
#include<string.h>
int main(){
  int n,t;
  char str[20];
  while(scanf("%s",str)!=EOF){
    n=strlen(str);
    for(t=n;t>=0;t--){
      printf("%c",a[t]);
    }
    printf("\n");
  }
  return (0);
}

Compiler output:
main.c: In function 'main':
main.c:9:19: error: 'a' undeclared (first use in this function)
    9 |       printf("%c",a[t]);
      |                   ^
main.c:9:19: note: each undeclared identifier is reported only once for each function it appears in
Language: C

#include <stdio.h>

int main(){
char moji[21]={'\0'};
int i,j,t,f;

scanf("%s",moji);
for(i=0;moji[i]!=\0;i++){
}
t=i;
for(j=0;j<t/2;j++){
f=moji[j];
moji[j]=moji[i-1];
moji[i-1]=f;
i--;
}
printf("%s\n",moji);

return 0;
}

Compiler output:
main.c: In function 'main':
main.c:8:18: error: stray '\' in program
    8 | for(i=0;moji[i]!=\0;i++){
      |                  ^
Language: C

#include<stdio.h>
#include<string.h>
int main(){
    char str[20];
    gets(str);
    puts(strrev(str));
}

Compiler output:
main.c: In function 'main':
main.c:5:5: error: implicit declaration of function 'gets'; did you mean 'fgets'? [-Wimplicit-function-declaration]
    5 |     gets(str);
      |     ^~~~
      |     fgets
main.c:6:10: error: implicit declaration of function 'strrev'; did you mean 'strsep'? [-Wimplicit-function-declaration]
    6 |     puts(strrev(str));
      |          ^~~~~~
      |          strsep
main.c:6:10: error: passing argument 1 of 'puts' makes pointer from integer without a cast [-Wint-conversion]
    6 |     puts(strrev(str));
      |          ^~~~~~~~~~~
      |          |
      |          int
In file included from main.c:1:
/usr/include/stdio.h:714:30: note: expected 'const char *' but argument is of type 'int'
  714 | extern int puts (const char *__s);
      |                  ~~~~~~~~~~~~^~~
Language: C

#include <stdio.h>

int main(void) {
    char str[20];
    int i;
    
    scanf("%s", str);
    
    for(i = 0; i < 20; i++) {
        if(str[i] != \0)
            printf("%c", str[i]);
    }
}

Compiler output:
main.c: In function 'main':
main.c:10:22: error: stray '\' in program
   10 |         if(str[i] != \0)
      |                      ^
Language: C

#include <Stdio.h>
#include <string.h>

int main(void) {
    char str[20];
    int i, len;
    
    scanf("%s", str);
    
    len = (int)strlen(str);
    
    for(i = len - 1; i >= 0; i--) {
        printf("%c", str[i]);
    }
    
    putchar('\n');
    
    return(0);
}

Compiler output:
main.c:1:10: fatal error: Stdio.h: No such file or directory
    1 | #include <Stdio.h>
      |          ^~~~~~~~~
compilation terminated.
Language: C

#include<stdio.h>

int main(){
	char str[21];
	int A;
	scanf("%s",str);
	for(A=0;str[A];A++);
	for(A--;A>=0;A--)
		printf("%c",str[A]);
	printf("\n")
	return 0;
}

Compiler output:
main.c: In function 'main':
main.c:10:21: error: expected ';' before 'return'
   10 |         printf("\n")
      |                     ^
      |                     ;
   11 |         return 0;
      |         ~~~~~~
Language: C

#include<stdio.h>
#include<string.h>
int main(void)
{
	int len;
	char str[20];
	scanf("%s",str);
	len=strlen(str)-1;
	for(i=len;i>=0;i--)
		putchar(str[i]);
	return 0;
}

Compiler output:
main.c: In function 'main':
main.c:9:13: error: 'i' undeclared (first use in this function)
    9 |         for(i=len;i>=0;i--)
      |             ^
main.c:9:13: note: each undeclared identifier is reported only once for each function it appears in
Language: C

#include <stdio.h>
int main()
{
    char ch[20]={'\0'};
    int i=0,n=0;
    for(i=0;i<20;i++)
    {
        ch[i]=getche();
        if(ch[i]=='\r')break;
        n++;
    }
    
    for(i=n-1;i>=0;i--)
        printf("%c",ch[i]);
    return 0;
}

Compiler output:
main.c: In function 'main':
main.c:8:15: error: implicit declaration of function 'getche'; did you mean 'getchar'? [-Wimplicit-function-declaration]
    8 |         ch[i]=getche();
      |               ^~~~~~
      |               getchar
Language: C

#include <iostream>
using namespace std;

int main(){

  string str,ans;
  int i;

  cin >> str;
  for(i = str.size() - 1 ; i != -1 ; i--){
    ans += str[i];
  }
  cout << ans << endl;

  return 0;
}

Compiler output:
main.c:1:10: fatal error: iostream: No such file or directory
    1 | #include <iostream>
      |          ^~~~~~~~~~
compilation terminated.
Language: C

#include <stdio.h>
#include <string.h>

int main()
{
   char arr[100];

   printf("\n");
   gets(arr);

   strrev(arr);

   printf("\n%s\n",arr);

   return 0;
}

Compiler output:
main.c: In function 'main':
main.c:9:4: error: implicit declaration of function 'gets'; did you mean 'fgets'? [-Wimplicit-function-declaration]
    9 |    gets(arr);
      |    ^~~~
      |    fgets
main.c:11:4: error: implicit declaration of function 'strrev'; did you mean 'strsep'? [-Wimplicit-function-declaration]
   11 |    strrev(arr);
      |    ^~~~~~
      |    strsep
Language: C

#include <stdio.h>
int main()
{
    char str[20];
    gets(str);
    strrev(str);
    puts(str);
    return 0;

}

Compiler output:
main.c: In function 'main':
main.c:5:5: error: implicit declaration of function 'gets'; did you mean 'fgets'? [-Wimplicit-function-declaration]
    5 |     gets(str);
      |     ^~~~
      |     fgets
main.c:6:5: error: implicit declaration of function 'strrev' [-Wimplicit-function-declaration]
    6 |     strrev(str);
      |     ^~~~~~
Language: C

#include <stdio.h>
#include <string.h>
int main()
{
    char str[20];
    int i;
    gets(str);
    strrev(str);
    puts(str);
    return 0;

}

Compiler output:
main.c: In function 'main':
main.c:7:5: error: implicit declaration of function 'gets'; did you mean 'fgets'? [-Wimplicit-function-declaration]
    7 |     gets(str);
      |     ^~~~
      |     fgets
main.c:8:5: error: implicit declaration of function 'strrev'; did you mean 'strsep'? [-Wimplicit-function-declaration]
    8 |     strrev(str);
      |     ^~~~~~
      |     strsep
Language: C

a = raw_input()

print a[::-1]

Compiler output:
main.c:1:1: warning: data definition has no type or storage class
    1 | a = raw_input()
      | ^
main.c:1:1: error: type defaults to 'int' in declaration of 'a' [-Wimplicit-int]
main.c:1:5: error: implicit declaration of function 'raw_input' [-Wimplicit-function-declaration]
    1 | a = raw_input()
      |     ^~~~~~~~~
main.c:1:5: error: initializer element is not constant
main.c:3:1: error: expected ',' or ';' before 'print'
    3 | print a[::-1]
      | ^~~~~
Language: C

#include<stdio.h>
#include<string.h>
int main(){
char ch[21],c;
int i=0,j;
gets(ch);
puts(strrev(ch));
return 0;
}

Compiler output:
main.c: In function 'main':
main.c:6:1: error: implicit declaration of function 'gets'; did you mean 'fgets'? [-Wimplicit-function-declaration]
    6 | gets(ch);
      | ^~~~
      | fgets
main.c:7:6: error: implicit declaration of function 'strrev'; did you mean 'strsep'? [-Wimplicit-function-declaration]
    7 | puts(strrev(ch));
      |      ^~~~~~
      |      strsep
main.c:7:6: error: passing argument 1 of 'puts' makes pointer from integer without a cast [-Wint-conversion]
    7 | puts(strrev(ch));
      |      ^~~~~~~~~~
      |      |
      |      int
In file included from main.c:1:
/usr/include/stdio.h:714:30: note: expected 'const char *' but argument is of type 'int'
  714 | extern int puts (const char *__s);
      |                  ~~~~~~~~~~~~^~~
Language: C

#include<stdio.h>
#include<string.h>

int main()
{
   char name[20];

   scanf("%s",name);

   printf("%s",strrev(name));

   return 0;
}

Compiler output:
main.c: In function 'main':
main.c:10:16: error: implicit declaration of function 'strrev'; did you mean 'strsep'? [-Wimplicit-function-declaration]
   10 |    printf("%s",strrev(name));
      |                ^~~~~~
      |                strsep
Language: C

main(i){char s[99];gets(s);for(i=strlen();i;)putchar(s[--i]);return!puts("");}

Compiler output:
main.c:1:1: error: return type defaults to 'int' [-Wimplicit-int]
    1 | main(i){char s[99];gets(s);for(i=strlen();i;)putchar(s[--i]);return!puts("");}
      | ^~~~
main.c: In function 'main':
main.c:1:1: error: type of 'i' defaults to 'int' [-Wimplicit-int]
main.c:1:20: error: implicit declaration of function 'gets' [-Wimplicit-function-declaration]
    1 | main(i){char s[99];gets(s);for(i=strlen();i;)putchar(s[--i]);return!puts("");}
      |                    ^~~~
main.c:1:34: error: implicit declaration of function 'strlen' [-Wimplicit-function-declaration]
    1 | main(i){char s[99];gets(s);for(i=strlen();i;)putchar(s[--i]);return!puts("");}
      |                                  ^~~~~~
main.c:1:1: note: include '<string.h>' or provide a declaration of 'strlen'
  +++ |+#include <string.h>
    1 | main(i){char s[99];gets(s);for(i=strlen();i;)putchar(s[--i]);return!puts("");}
main.c:1:34: warning: incompatible implicit declaration of built-in function 'strlen' [-Wbuiltin-declaration-mismatch]
    1 | main(i){char s[99];gets(s);for(i=strlen();i;)putchar(s[--i]);return!puts("");}
      |                                  ^~~~~~
main.c:1:34: note: include '<string.h>' or provide a declaration of 'strlen'
main.c:1:34: error: too few arguments to function 'strlen'
main.c:1:46: error: implicit declaration of function 'putchar' [-Wimplicit-function-declaration]
    1 | main(i){char s[99];gets(s);for(i=strlen();i;)putchar(s[--i]);return!puts("");}
      |                                              ^~~~~~~
main.c:1:1: note: include '<stdio.h>' or provide a declaration of 'putchar'
  +++ |+#include <stdio.h>
    1 | main(i){char s[99];gets(s);for(i=strlen();i;)putchar(s[--i]);return!puts("");}
main.c:1:69: error: implicit declaration of function 'puts' [-Wimplicit-function-declaration]
    1 | main(i){char s[99];gets(s);for(i=strlen();i;)putchar(s[--i]);return!puts("");}
      |                                                                     ^~~~
main.c:1:69: note: include '<stdio.h>' or provide a declaration of 'puts'
Language: C++

#include <bits/stdc++.h>

int main () {
assdasd
asd
a
sd
a
sda
sd
a
s
d
as
d
as
dassssssssssssssssssss
}


Compiler output:
a.cc: In function 'int main()':
a.cc:4:1: error: 'assdasd' was not declared in this scope
    4 | assdasd
      | ^~~~~~~
Language: C++

#include <iostream>

#include <string>

#include <algorithm>



using namespace std;



int main(){

	string str;

	cin >> str;

	reverse(str.begin(),str.end());

	cout << x << endl;

	return 0;

}	

	


Compiler output:
a.cc: In function 'int main()':
a.cc:21:17: error: 'x' was not declared in this scope
   21 |         cout << x << endl;
      |                 ^
Language: C++

#include<iostream>
#include<string>

using namespace std;

int main() {
  string s;
  cin >> s;
  reverse(s.begin(),s.end());
  cout << s << endl;
  return 0;
}



Compiler output:
a.cc: In function 'int main()':
a.cc:9:3: error: 'reverse' was not declared in this scope
    9 |   reverse(s.begin(),s.end());
      |   ^~~~~~~
Language: C++

#include<iostream>
#include<string>
using namespace std;

int main() {
	string str,a;
	a = 0
	cin >> str;
	for(i =str.size()-1;i>=0;i--){
		a += str[i];


	}
	cout << a << endl;
	
	return 0;
}




Compiler output:
a.cc: In function 'int main()':
a.cc:7:13: error: ambiguous overload for 'operator=' (operand types are 'std::string' {aka 'std::__cxx11::basic_string<char>'} and 'int')
    7 |         a = 0
      |             ^
In file included from /usr/include/c++/14/string:54,
                 from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/basic_string.h:817:7: note: candidate: 'std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator=(const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]'
  817 |       operator=(const basic_string& __str)
      |       ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:828:7: note: candidate: 'std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator=(const _CharT*) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]'
  828 |       operator=(const _CharT* __s)
      |       ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:840:7: note: candidate: 'std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator=(_CharT) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]'
  840 |       operator=(_CharT __c)
      |       ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:858:7: note: candidate: 'std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator=(std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]'
  858 |       operator=(basic_string&& __str)
      |       ^~~~~~~~
a.cc:9:13: error: 'i' was not declared in this scope
    9 |         for(i =str.size()-1;i>=0;i--){
      |             ^
Language: C++

#include<iostream>
#include<string>
using namespace std;

int main() {
	string str,a;
	a = 0
	cin >> str;
	for(int i =str.size()-1;i>=0;i--){
		a += str[i];


	}
	cout << a << endl;
	
	return 0;
}




Compiler output:
a.cc: In function 'int main()':
a.cc:7:13: error: ambiguous overload for 'operator=' (operand types are 'std::string' {aka 'std::__cxx11::basic_string<char>'} and 'int')
    7 |         a = 0
      |             ^
In file included from /usr/include/c++/14/string:54,
                 from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/basic_string.h:817:7: note: candidate: 'std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator=(const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]'
  817 |       operator=(const basic_string& __str)
      |       ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:828:7: note: candidate: 'std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator=(const _CharT*) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]'
  828 |       operator=(const _CharT* __s)
      |       ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:840:7: note: candidate: 'std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator=(_CharT) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]'
  840 |       operator=(_CharT __c)
      |       ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:858:7: note: candidate: 'std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator=(std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]'
  858 |       operator=(basic_string&& __str)
      |       ^~~~~~~~
Language: C++

#include<iostream>
using namespace std;
int main () {
    string mozi;
    cin >> mozi;
    int y;
    y = mozi.length();
    for(i=0;i<y;++i){
        string reverse;
        reverse[i]=mozi[y-i];
    }
    cout << reverse << endl;
    return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:8:9: error: 'i' was not declared in this scope
    8 |     for(i=0;i<y;++i){
      |         ^
a.cc:12:13: error: 'reverse' was not declared in this scope
   12 |     cout << reverse << endl;
      |             ^~~~~~~
Language: C++

#include<iostream>
using namespace std;
int main () {
    string mozi;
    cin >> mozi;
    int y;
    y = mozi.length();
    for(int i=0;i<y;++i){
        string reverse;
        reverse[i]=mozi[y-i];
    }
    cout << reverse << endl;
    return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:12:13: error: 'reverse' was not declared in this scope
   12 |     cout << reverse << endl;
      |             ^~~~~~~
Language: C++

//============================================================================
// Name        : 0006.cpp
// Author      : 
// Version     :
// Copyright   : Your copyright notice
// Description : Hello World in C++, Ansi-style
//============================================================================

#include <iostream>
using namespace std;

int main() {
	string s;
	while( cin >> s ){
		reverse(s.begin() , s.end());
		cout << s <<endl;
	}
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:15:17: error: 'reverse' was not declared in this scope
   15 |                 reverse(s.begin() , s.end());
      |                 ^~~~~~~
Language: C++

#include <cstdio>
#include <cmath>
#include <cstring>
#include <cstdlib>
#include <climits>
#include <ctime>
#include <queue>
#include <stack>
#include <algorithm>
#include <list>
#include <vector>
#include <set>
#include <map>
#include <iostream>
#include <deque>
#include <complex>
#include <string>
#include <iomanip>
#include <sstream>
#include <bitset>
#include <valarray>
#include <iterator>
using namespace std;
typedef long long int ll;
typedef unsigned int uint;
typedef unsigned char uchar;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef vector<int> vi;

#define REP(i,x) for(int i=0;i<(int)(x);i++)
#define FOR(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();i++)
#define RREP(i,x) for(int i=((int)(x)-1);i>=0;i--)
#define RFOR(i,c) for(__typeof((c).rbegin())i=(c).rbegin();i!=(c).rend();i++)
#define ALL(container) container.begin(), container.end()
#define RALL(container) container.rbegin(), container.rend()
#define SZ(container) ((int)container.size())
#define mp(a,b) make_pair(a, b)
#define UNIQUE(v) v.erase( unique(v.begin(), v.end()), v.end() );

template<class T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1; } return 0; }
template<class T> ostream& operator<<(ostream &os, const vector<T> &t) {
os<<"["; FOR(it,t) {if(it!=t.begin()) os<<","; os<<*it;} os<<"]"; return os;
}
template<class T> ostream& operator<<(ostream &os, const set<T> &t) {
os<<"{"; FOR(it,t) {if(it!=t.begin()) os<<","; os<<*it;} os<<"}"; return os;
}
template<class S, class T> ostream& operator<<(ostream &os, const pair<S,T> &t) { return os<<"("<<t.first<<","<<t.second<<")";}

const int INF = 1<<28;
const double EPS = 1e-8;
const int MOD = 1000000007;


string s

main(){
	while(cin >> s){
reverse(ALL(s));
		cout << s << endl;
	}
	return 0;
}

Compiler output:
a.cc:58:1: error: expected initializer before 'main'
   58 | main(){
      | ^~~~
Language: C++

#include<stdio.h>
#include<string.h>

int main(){

int i,len;
char str[22];

scanf'("%s",str);

len=strlen(str);

for(i=len-1;i>=0;i--){
printf("%c",str[i]);
}
printf("\n");

return 0;
}

Compiler output:
a.cc:9:6: warning: missing terminating ' character
    9 | scanf'("%s",str);
      |      ^
a.cc:9:6: error: missing terminating ' character
    9 | scanf'("%s",str);
      |      ^~~~~~~~~~~~
a.cc: In function 'int main()':
a.cc:9:6: error: expected ';' before 'len'
    9 | scanf'("%s",str);
      |      ^
      |      ;
   10 | 
   11 | len=strlen(str);
      | ~~~
Language: C++

#include<iostream>
#include<string>
using namespace std;

int main()
{
  string str;
  getline(cin,str);
  reverse(str.begin(),str.end());
  cout << str<<endl;
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:9:3: error: 'reverse' was not declared in this scope
    9 |   reverse(str.begin(),str.end());
      |   ^~~~~~~
Language: C++

#include<iostream>
#include<string>
using namespace std;

int main()
{
  string str;
  getline(cin,str);
  reverse(begin(str),end(str));
  cout << str<<endl;
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:9:3: error: 'reverse' was not declared in this scope
    9 |   reverse(begin(str),end(str));
      |   ^~~~~~~
Language: C++

#include<iostream>
#include<string>
using namespace std;

int main()
{
  string str;
  cin>>str;
  reverse(begin(str),end(str));
  cout << str<<endl;
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:9:3: error: 'reverse' was not declared in this scope
    9 |   reverse(begin(str),end(str));
      |   ^~~~~~~
Language: C++

#include <iostream>
#include <string>

int main()
{
  std::string str;
  while (std::cin >> str) {
    for (size_t  i = str.size() - 1; i != 0; --i) {
      std::cout << str[i];
    }
    std::cout << endl;
  }

  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:11:18: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   11 |     std::cout << endl;
      |                  ^~~~
      |                  std::endl
In file included from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/ostream:744:5: note: 'std::endl' declared here
  744 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~
Language: C++

#include<iostream>
#include<algorithm>
#include<cstdio>

using namespace std;

int main()
{
    char s[20];
    int n,T;
    while(cin>>s){
       n=strlen(s);
       
       for(int i=0;i<(n/2);i++){
          T=s[i];
          s[i]=s[n-i-1];
          s[n-i-1]=T;        
       }             
       cout<<s<<endl; 
    }
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:12:10: error: 'strlen' was not declared in this scope
   12 |        n=strlen(s);
      |          ^~~~~~
a.cc:4:1: note: 'strlen' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'
    3 | #include<cstdio>
  +++ |+#include <cstring>
    4 |
Language: C++



#include<cstdio>
#include<cstring>

using namespace std;

int main()
{
    char s[20];
    int n,T;
    while(cin>>s){
       n=strlen(s);
       
       for(int i=0;i<(n/2);i++){
          T=s[i];
          s[i]=s[n-i-1];
          s[n-i-1]=T;        
       }             
       cout<<s<<endl; 
    }
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:12:11: error: 'cin' was not declared in this scope
   12 |     while(cin>>s){
      |           ^~~
a.cc:5:1: note: 'std::cin' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
    4 | #include<cstring>
  +++ |+#include <iostream>
    5 | 
a.cc:20:8: error: 'cout' was not declared in this scope
   20 |        cout<<s<<endl;
      |        ^~~~
a.cc:20:8: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:20:17: error: 'endl' was not declared in this scope
   20 |        cout<<s<<endl;
      |                 ^~~~
a.cc:5:1: note: 'std::endl' is defined in header '<ostream>'; this is probably fixable by adding '#include <ostream>'
    4 | #include<cstring>
  +++ |+#include <ostream>
    5 |
Language: C++

#include <cstdio>
#include <iostream>
#include <algorithm>
using namespace std;
 
int main() {
    char a[25], i;
    scanf("%s", a);
    for(i=strlen(a)-1;i>=0;i--){
       printf("%c", a[i]);                         
                             
    }
    printf("\n");
    
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:9:11: error: 'strlen' was not declared in this scope
    9 |     for(i=strlen(a)-1;i>=0;i--){
      |           ^~~~~~
a.cc:4:1: note: 'strlen' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'
    3 | #include <algorithm>
  +++ |+#include <cstring>
    4 | using namespace std;
Language: C++

#include <cstdio>
#include <iostream>
#include <algorithm>
using namespace std;
 
int main() {
    char a[25], i;
    scanf("%s", &a);
    for(i=strlen(a)-1;i>=0;i--){
       printf("%c", a[i]);                         
                             
    }
    printf("\n");
    
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:9:11: error: 'strlen' was not declared in this scope
    9 |     for(i=strlen(a)-1;i>=0;i--){
      |           ^~~~~~
a.cc:4:1: note: 'strlen' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'
    3 | #include <algorithm>
  +++ |+#include <cstring>
    4 | using namespace std;
Language: C++

#include<stdio.h>
#include<string.h>
int main()
{
    char s[20];
    gets(s);
    strrev(s);
    puts(s);
    printf("\n");
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:6:5: error: 'gets' was not declared in this scope; did you mean 'getw'?
    6 |     gets(s);
      |     ^~~~
      |     getw
a.cc:7:5: error: 'strrev' was not declared in this scope; did you mean 'strsep'?
    7 |     strrev(s);
      |     ^~~~~~
      |     strsep
Language: C++

#include <stdio.h>
#include <string.h>

int main()
{
    char str[19];

   gets(str);

   strrev(str);

   printf("%s\n",str);

   return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:8:4: error: 'gets' was not declared in this scope; did you mean 'getw'?
    8 |    gets(str);
      |    ^~~~
      |    getw
a.cc:10:4: error: 'strrev' was not declared in this scope; did you mean 'strsep'?
   10 |    strrev(str);
      |    ^~~~~~
      |    strsep
Language: C++

#include <stdio.h>
#include <string.h>
int main ()
{
char str[20];
while(scanf("%s",str)!=EOF)
{
	strrev(str);
printf("%s",str);
printf("\n");
}
return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:8:9: error: 'strrev' was not declared in this scope; did you mean 'strsep'?
    8 |         strrev(str);
      |         ^~~~~~
      |         strsep
Language: C++

 #include<stdio.h>

 int main ()
 {
     char str[20],s2[20];

     scanf("%s",str);
     int i,len=0;

     for (i=0;str[i]!='\0';i++)
     {
         len++;
     }

     strrev(str);

     for (i=0;i<len;i++)
     printf ("%c", str[i]);
     printf ("\n");
     return 0;
 }

Compiler output:
a.cc: In function 'int main()':
a.cc:15:6: error: 'strrev' was not declared in this scope
   15 |      strrev(str);
      |      ^~~~~~
Language: C++

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace coding
{
    class Program
    {
        static void Main(string[] args)
        {
            string input = Console.ReadLine();
            string output = "";             
            for (int i = input.Length - 1; i >= 0; i--)
            {
                output = output + input[i];
            }
            Console.WriteLine(output);
        }
    }
}

Compiler output:
a.cc:1:7: error: expected nested-name-specifier before 'System'
    1 | using System;
      |       ^~~~~~
a.cc:2:7: error: expected nested-name-specifier before 'System'
    2 | using System.Collections.Generic;
      |       ^~~~~~
a.cc:3:7: error: expected nested-name-specifier before 'System'
    3 | using System.Linq;
      |       ^~~~~~
a.cc:4:7: error: expected nested-name-specifier before 'System'
    4 | using System.Text;
      |       ^~~~~~
a.cc:5:7: error: expected nested-name-specifier before 'System'
    5 | using System.Threading.Tasks;
      |       ^~~~~~
a.cc:11:26: error: 'string' has not been declared
   11 |         static void Main(string[] args)
      |                          ^~~~~~
a.cc:11:35: error: expected ',' or '...' before 'args'
   11 |         static void Main(string[] args)
      |                                   ^~~~
a.cc:21:6: error: expected ';' after class definition
   21 |     }
      |      ^
      |      ;
a.cc: In static member function 'static void coding::Program::Main(int*)':
a.cc:13:13: error: 'string' was not declared in this scope
   13 |             string input = Console.ReadLine();
      |             ^~~~~~
a.cc:14:20: error: expected ';' before 'output'
   14 |             string output = "";
      |                    ^~~~~~
a.cc:15:26: error: 'input' was not declared in this scope; did you mean 'int'?
   15 |             for (int i = input.Length - 1; i >= 0; i--)
      |                          ^~~~~
      |                          int
a.cc:17:17: error: 'output' was not declared in this scope
   17 |                 output = output + input[i];
      |                 ^~~~~~
a.cc:19:13: error: 'Console' was not declared in this scope
   19 |             Console.WriteLine(output);
      |             ^~~~~~~
a.cc:19:31: error: 'output' was not declared in this scope
   19 |             Console.WriteLine(output);
      |                               ^~~~~~
Language: C++

#include <stdio.h>
#include <string.h>

int main()
{
char str[20];
 gets(str);
 strrev(str);
 printf("%s\n",str);
 return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:7:2: error: 'gets' was not declared in this scope; did you mean 'getw'?
    7 |  gets(str);
      |  ^~~~
      |  getw
a.cc:8:2: error: 'strrev' was not declared in this scope; did you mean 'strsep'?
    8 |  strrev(str);
      |  ^~~~~~
      |  strsep
Language: C++

line = input()

ret = "";
for i in range(1,len(line)):
	ret += line[len(line)-1-i];

print(ret)

Compiler output:
a.cc:1:1: error: 'line' does not name a type
    1 | line = input()
      | ^~~~
a.cc:4:1: error: expected unqualified-id before 'for'
    4 | for i in range(1,len(line)):
      | ^~~
a.cc:7:6: error: expected constructor, destructor, or type conversion before '(' token
    7 | print(ret)
      |      ^
Language: C++

#include<stdio.h>
#include<iostream>
#include<math.h>
#include<algorithm>
#include<string>
#include<string.h>
#include<stack>
#include<queue>
#include<stdlib.h>
#include<ctype.h>
#include<map>
#include<iomanip>
#define r 6371.01
#define pi 3.141592653589
#define PI acos(0.0)
#define EPS 1e-7

using namespace std;
int main()
{
    char str[20];
    scanf("%s",&str);
    printf("%s\n",strrev(str));
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:23:19: error: 'strrev' was not declared in this scope; did you mean 'strsep'?
   23 |     printf("%s\n",strrev(str));
      |                   ^~~~~~
      |                   strsep
Language: C++

#include <stdio.h>

int main(void) {
	char str[20];
	int i;
	scanf("%s",str);
	for(i = 0; strlen(str) > i; i++){
		printf("%c",str[strlen(str)-1 - i]);
	}
	printf("\n");
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:7:20: error: 'strlen' was not declared in this scope
    7 |         for(i = 0; strlen(str) > i; i++){
      |                    ^~~~~~
a.cc:2:1: note: 'strlen' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'
    1 | #include <stdio.h>
  +++ |+#include <cstring>
    2 |
Language: C++

import java.util.Scanner;
import java.lang.StringBuffer;

class Main{
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        StringBuffer sb = new StringBuffer(in.nextLine());
        System.out.println(sb.reverse().toString());
    }
}

Compiler output:
a.cc:1:1: error: 'import' does not name a type
    1 | import java.util.Scanner;
      | ^~~~~~
a.cc:1:1: note: C++20 'import' only available with '-fmodules-ts'
a.cc:2:1: error: 'import' does not name a type
    2 | import java.lang.StringBuffer;
      | ^~~~~~
a.cc:2:1: note: C++20 'import' only available with '-fmodules-ts'
a.cc:5:11: error: expected ':' before 'static'
    5 |     public static void main(String[] args){
      |           ^~~~~~~
      |           :
a.cc:5:29: error: 'String' has not been declared
    5 |     public static void main(String[] args){
      |                             ^~~~~~
a.cc:5:38: error: expected ',' or '...' before 'args'
    5 |     public static void main(String[] args){
      |                                      ^~~~
a.cc:10:2: error: expected ';' after class definition
   10 | }
      |  ^
      |  ;
a.cc: In static member function 'static void Main::main(int*)':
a.cc:6:9: error: 'Scanner' was not declared in this scope
    6 |         Scanner in = new Scanner(System.in);
      |         ^~~~~~~
a.cc:7:9: error: 'StringBuffer' was not declared in this scope
    7 |         StringBuffer sb = new StringBuffer(in.nextLine());
      |         ^~~~~~~~~~~~
a.cc:8:9: error: 'System' was not declared in this scope
    8 |         System.out.println(sb.reverse().toString());
      |         ^~~~~~
a.cc:8:28: error: 'sb' was not declared in this scope
    8 |         System.out.println(sb.reverse().toString());
      |                            ^~
Language: C++

#include <cstdio>
#include <cstring>
using namespace std;

int main(){
	char str[25];
	
	fill(str, str + 25, 0);
	
	scanf("%s", str);
	
	int p = 25;
	while(str[--p] == 0);
	while(p >= 0){
		printf("%c", str[p--]);
	}
	
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:8:9: error: 'fill' was not declared in this scope
    8 |         fill(str, str + 25, 0);
      |         ^~~~
Language: C++

#include <iostream>
#include <string>
using namespace std;

int main(){
	string s;
	cin >> s;
	reverse(s.begin(),s.end());
	cout << s << endl;
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:8:9: error: 'reverse' was not declared in this scope
    8 |         reverse(s.begin(),s.end());
      |         ^~~~~~~