Language: C

#include<stdio.h>
#include<string.h> //strcmp、strncmp関数を使うために必要
 
int main(void){
  	char =*a;
	scanf("%s",&a);
  switch(a){
    case a:printf("a");
          break;
      case b:printf("a");
          break;
      case c:printf("a");
          break;
      case d:printf("a");
          break;
      case e:printf("a");
          break;
      case f:printf("a");
          break;
      case g:printf("a");
          break;
      case h:printf("a");
          break;
      case i:printf("a");
          break;
      case j:printf("a");
          break;
      case k:printf("a");
          break;
      case l:printf("a");
          break;
      case m:printf("a");
          break;
      case n:printf("a");
          break;
      case o:printf("a");
          break;
      case p:printf("a");
          break;
      case q:printf("a");
          break;
      case r:printf("a");
          break;
      case s:printf("a");
          break;
      case t:printf("a");
          break;
      case u:printf("a");
          break;
      case v:printf("a");
          break;
      case w:printf("a");
          break;
      case x:printf("a");
          break;
      case y:printf("a");
          break;
      case z:printf("a");
          break;
     default :printf("A");
      			break;

  }

		return 0;
}

Compiler output:
main.c: In function 'main':
main.c:5:14: error: expected identifier or '(' before '=' token
    5 |         char =*a;
      |              ^
main.c:6:21: error: 'a' undeclared (first use in this function)
    6 |         scanf("%s",&a);
      |                     ^
main.c:6:21: note: each undeclared identifier is reported only once for each function it appears in
main.c:10:12: error: 'b' undeclared (first use in this function)
   10 |       case b:printf("a");
      |            ^
main.c:12:12: error: 'c' undeclared (first use in this function)
   12 |       case c:printf("a");
      |            ^
main.c:14:12: error: 'd' undeclared (first use in this function)
   14 |       case d:printf("a");
      |            ^
main.c:16:12: error: 'e' undeclared (first use in this function)
   16 |       case e:printf("a");
      |            ^
main.c:18:12: error: 'f' undeclared (first use in this function)
   18 |       case f:printf("a");
      |            ^
main.c:20:12: error: 'g' undeclared (first use in this function)
   20 |       case g:printf("a");
      |            ^
main.c:22:12: error: 'h' undeclared (first use in this function)
   22 |       case h:printf("a");
      |            ^
main.c:24:12: error: 'i' undeclared (first use in this function)
   24 |       case i:printf("a");
      |            ^
main.c:26:12: error: 'j' undeclared (first use in this function)
   26 |       case j:printf("a");
      |            ^
main.c:28:12: error: 'k' undeclared (first use in this function)
   28 |       case k:printf("a");
      |            ^
main.c:30:12: error: 'l' undeclared (first use in this function)
   30 |       case l:printf("a");
      |            ^
main.c:32:12: error: 'm' undeclared (first use in this function)
   32 |       case m:printf("a");
      |            ^
main.c:34:12: error: 'n' undeclared (first use in this function)
   34 |       case n:printf("a");
      |            ^
main.c:36:12: error: 'o' undeclared (first use in this function)
   36 |       case o:printf("a");
      |            ^
main.c:38:12: error: 'p' undeclared (first use in this function)
   38 |       case p:printf("a");
      |            ^
main.c:40:12: error: 'q' undeclared (first use in this function)
   40 |       case q:printf("a");
      |            ^
main.c:42:12: error: 'r' undeclared (first use in this function)
   42 |       case r:printf("a");
      |            ^
main.c:44:12: error: 's' undeclared (first use in this function)
   44 |       case s:printf("a");
      |            ^
main.c:46:12: error: 't' undeclared (first use in this function)
   46 |       case t:printf("a");
      |            ^
main.c:48:12: error: 'u' undeclared (first use in this function)
   48 |       case u:printf("a");
      |            ^
main.c:50:12: error: 'v' undeclared (first use in this function)
   50 |       case v:printf("a");
      |            ^
main.c:52:12: error: 'w' undeclared (first use in this function)
   52 |       case w:printf("a");
      |            ^
main.c:54:12: error: 'x' undeclared (first use in this function)
   54 |       case x:printf("a");
      |            ^
main.c:56:12: error: 'y' undeclared (first use in this function)
   56 |       case y:printf("a");
      |            ^
main.c:58:12: error: 'z' undeclared (first use in this function)
   58 |       case z:printf("a");
      |            ^