Language: C

#include<stdio.h>
#include<string.h>
int main()
{
string a[100], b[100], c[100];
int i, j, m,n,t;
getline(cin,a);
getline(cin,b);
m=strlen(a);
n=strlen(b);
if(m=n)
t=2*n;
else
t=m+n;
for(i=0;i<t;i++)
{ 
if((i+1)%2==0)
 c[i]=a[i];
else
c[i]=b[i];
}
c[t]='\0';
puts(c);
return 0;
}

Compiler output:
main.c: In function 'main':
main.c:5:1: error: unknown type name 'string'; did you mean 'stdin'?
    5 | string a[100], b[100], c[100];
      | ^~~~~~
      | stdin
main.c:7:9: error: 'cin' undeclared (first use in this function)
    7 | getline(cin,a);
      |         ^~~
main.c:7:9: note: each undeclared identifier is reported only once for each function it appears in
main.c:7:13: error: passing argument 2 of 'getline' from incompatible pointer type [-Wincompatible-pointer-types]
    7 | getline(cin,a);
      |             ^
      |             |
      |             int *
In file included from main.c:1:
/usr/include/stdio.h:698:46: note: expected 'size_t * restrict' {aka 'long unsigned int * restrict'} but argument is of type 'int *'
  698 |                           size_t *__restrict __n,
      |                           ~~~~~~~~~~~~~~~~~~~^~~
main.c:7:1: error: too few arguments to function 'getline'
    7 | getline(cin,a);
      | ^~~~~~~
/usr/include/stdio.h:697:18: note: declared here
  697 | extern __ssize_t getline (char **__restrict __lineptr,
      |                  ^~~~~~~
main.c:8:13: error: passing argument 2 of 'getline' from incompatible pointer type [-Wincompatible-pointer-types]
    8 | getline(cin,b);
      |             ^
      |             |
      |             int *
/usr/include/stdio.h:698:46: note: expected 'size_t * restrict' {aka 'long unsigned int * restrict'} but argument is of type 'int *'
  698 |                           size_t *__restrict __n,
      |                           ~~~~~~~~~~~~~~~~~~~^~~
main.c:8:1: error: too few arguments to function 'getline'
    8 | getline(cin,b);
      | ^~~~~~~
/usr/include/stdio.h:697:18: note: declared here
  697 | extern __ssize_t getline (char **__restrict __lineptr,
      |                  ^~~~~~~
main.c:9:10: error: passing argument 1 of 'strlen' from incompatible pointer type [-Wincompatible-pointer-types]
    9 | m=strlen(a);
      |          ^
      |          |
      |          int *
In file included from main.c:2:
/usr/include/string.h:407:35: note: expected 'const char *' but argument is of type 'int *'
  407 | extern size_t strlen (const char *__s)
      |                       ~~~~~~~~~~~~^~~
main.c:10:10: error: passing argument 1 of 'strlen' from incompatible pointer type [-Wincompatible-pointer-types]
   10 | n=strlen(b);
      |          ^
      |          |
      |          int *
/usr/include/string.h:407:35: note: expected 'const char *' but argument is of type 'int *'
  407 | extern size_t strlen (const char *__s)
      |                       ~~~~~~~~~~~~^~~
main.c:23:6: error: passing argument 1 of 'puts' from incompatible pointer type [-Wincompatible-pointer-types]
   23 | puts(c);
      |      ^
      |      |
      |      int *
/usr/include/stdio.h:714:30: note: expected 'const char *' but argument is of type 'int *'
  714 | extern int puts (const char *__s);
      |                  ~~~~~~~~~~~~^~~