Language: C

main(a,b){for(;~scanf("%d%d",&a,&b);printf("%d\n",sprintf((char*)&a,"%d",a+b)));exit(0)}

Compiler output:
main.c:1:1: error: return type defaults to 'int' [-Wimplicit-int]
    1 | main(a,b){for(;~scanf("%d%d",&a,&b);printf("%d\n",sprintf((char*)&a,"%d",a+b)));exit(0)}
      | ^~~~
main.c: In function 'main':
main.c:1:1: error: type of 'a' defaults to 'int' [-Wimplicit-int]
main.c:1:1: error: type of 'b' defaults to 'int' [-Wimplicit-int]
main.c:1:17: error: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
    1 | main(a,b){for(;~scanf("%d%d",&a,&b);printf("%d\n",sprintf((char*)&a,"%d",a+b)));exit(0)}
      |                 ^~~~~
main.c:1:1: note: include '<stdio.h>' or provide a declaration of 'scanf'
  +++ |+#include <stdio.h>
    1 | main(a,b){for(;~scanf("%d%d",&a,&b);printf("%d\n",sprintf((char*)&a,"%d",a+b)));exit(0)}
main.c:1:17: warning: incompatible implicit declaration of built-in function 'scanf' [-Wbuiltin-declaration-mismatch]
    1 | main(a,b){for(;~scanf("%d%d",&a,&b);printf("%d\n",sprintf((char*)&a,"%d",a+b)));exit(0)}
      |                 ^~~~~
main.c:1:17: note: include '<stdio.h>' or provide a declaration of 'scanf'
main.c:1:37: error: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
    1 | main(a,b){for(;~scanf("%d%d",&a,&b);printf("%d\n",sprintf((char*)&a,"%d",a+b)));exit(0)}
      |                                     ^~~~~~
main.c:1:37: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:1:37: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
main.c:1:37: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:1:51: error: implicit declaration of function 'sprintf' [-Wimplicit-function-declaration]
    1 | main(a,b){for(;~scanf("%d%d",&a,&b);printf("%d\n",sprintf((char*)&a,"%d",a+b)));exit(0)}
      |                                                   ^~~~~~~
main.c:1:51: note: include '<stdio.h>' or provide a declaration of 'sprintf'
main.c:1:51: warning: incompatible implicit declaration of built-in function 'sprintf' [-Wbuiltin-declaration-mismatch]
main.c:1:51: note: include '<stdio.h>' or provide a declaration of 'sprintf'
main.c:1:81: error: implicit declaration of function 'exit' [-Wimplicit-function-declaration]
    1 | main(a,b){for(;~scanf("%d%d",&a,&b);printf("%d\n",sprintf((char*)&a,"%d",a+b)));exit(0)}
      |                                                                                 ^~~~
main.c:1:1: note: include '<stdlib.h>' or provide a declaration of 'exit'
  +++ |+#include <stdlib.h>
    1 | main(a,b){for(;~scanf("%d%d",&a,&b);printf("%d\n",sprintf((char*)&a,"%d",a+b)));exit(0)}
main.c:1:81: warning: incompatible implicit declaration of built-in function 'exit' [-Wbuiltin-declaration-mismatch]
    1 | main(a,b){for(;~scanf("%d%d",&a,&b);printf("%d\n",sprintf((char*)&a,"%d",a+b)));exit(0)}
      |                                                                                 ^~~~
main.c:1:81: note: include '<stdlib.h>' or provide a declaration of 'exit'
main.c:1:88: error: expected ';' before '}' token
    1 | main(a,b){for(;~scanf("%d%d",&a,&b);printf("%d\n",sprintf((char*)&a,"%d",a+b)));exit(0)}
      |                                                                                        ^
      |                                                                                        ;