Language: C

main ()double a,b,c,d,e,f;{for(;scanf("%f %f %f %f %f %F",&a,&b,&c,&d,&e,&f)!=EOF;printf("%f %f\n",(e*c-f*b)/(e*a-b*d),(a*f-c*d)/(a*e-b*d))));return 0;}

Compiler output:
main.c:1:1: error: return type defaults to 'int' [-Wimplicit-int]
    1 | main ()double a,b,c,d,e,f;{for(;scanf("%f %f %f %f %f %F",&a,&b,&c,&d,&e,&f)!=EOF;printf("%f %f\n",(e*c-f*b)/(e*a-b*d),(a*f-c*d)/(a*e-b*d))));return 0;}
      | ^~~~
main.c: In function 'main':
main.c:1:25: error: declaration for parameter 'f' but no such parameter
    1 | main ()double a,b,c,d,e,f;{for(;scanf("%f %f %f %f %f %F",&a,&b,&c,&d,&e,&f)!=EOF;printf("%f %f\n",(e*c-f*b)/(e*a-b*d),(a*f-c*d)/(a*e-b*d))));return 0;}
      |                         ^
main.c:1:23: error: declaration for parameter 'e' but no such parameter
    1 | main ()double a,b,c,d,e,f;{for(;scanf("%f %f %f %f %f %F",&a,&b,&c,&d,&e,&f)!=EOF;printf("%f %f\n",(e*c-f*b)/(e*a-b*d),(a*f-c*d)/(a*e-b*d))));return 0;}
      |                       ^
main.c:1:21: error: declaration for parameter 'd' but no such parameter
    1 | main ()double a,b,c,d,e,f;{for(;scanf("%f %f %f %f %f %F",&a,&b,&c,&d,&e,&f)!=EOF;printf("%f %f\n",(e*c-f*b)/(e*a-b*d),(a*f-c*d)/(a*e-b*d))));return 0;}
      |                     ^
main.c:1:19: error: declaration for parameter 'c' but no such parameter
    1 | main ()double a,b,c,d,e,f;{for(;scanf("%f %f %f %f %f %F",&a,&b,&c,&d,&e,&f)!=EOF;printf("%f %f\n",(e*c-f*b)/(e*a-b*d),(a*f-c*d)/(a*e-b*d))));return 0;}
      |                   ^
main.c:1:17: error: declaration for parameter 'b' but no such parameter
    1 | main ()double a,b,c,d,e,f;{for(;scanf("%f %f %f %f %f %F",&a,&b,&c,&d,&e,&f)!=EOF;printf("%f %f\n",(e*c-f*b)/(e*a-b*d),(a*f-c*d)/(a*e-b*d))));return 0;}
      |                 ^
main.c:1:15: error: declaration for parameter 'a' but no such parameter
    1 | main ()double a,b,c,d,e,f;{for(;scanf("%f %f %f %f %f %F",&a,&b,&c,&d,&e,&f)!=EOF;printf("%f %f\n",(e*c-f*b)/(e*a-b*d),(a*f-c*d)/(a*e-b*d))));return 0;}
      |               ^
main.c:1:33: error: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
    1 | main ()double a,b,c,d,e,f;{for(;scanf("%f %f %f %f %f %F",&a,&b,&c,&d,&e,&f)!=EOF;printf("%f %f\n",(e*c-f*b)/(e*a-b*d),(a*f-c*d)/(a*e-b*d))));return 0;}
      |                                 ^~~~~
main.c:1:1: note: include '<stdio.h>' or provide a declaration of 'scanf'
  +++ |+#include <stdio.h>
    1 | main ()double a,b,c,d,e,f;{for(;scanf("%f %f %f %f %f %F",&a,&b,&c,&d,&e,&f)!=EOF;printf("%f %f\n",(e*c-f*b)/(e*a-b*d),(a*f-c*d)/(a*e-b*d))));return 0;}
main.c:1:33: warning: incompatible implicit declaration of built-in function 'scanf' [-Wbuiltin-declaration-mismatch]
    1 | main ()double a,b,c,d,e,f;{for(;scanf("%f %f %f %f %f %F",&a,&b,&c,&d,&e,&f)!=EOF;printf("%f %f\n",(e*c-f*b)/(e*a-b*d),(a*f-c*d)/(a*e-b*d))));return 0;}
      |                                 ^~~~~
main.c:1:33: note: include '<stdio.h>' or provide a declaration of 'scanf'
main.c:1:79: error: 'EOF' undeclared (first use in this function)
    1 | main ()double a,b,c,d,e,f;{for(;scanf("%f %f %f %f %f %F",&a,&b,&c,&d,&e,&f)!=EOF;printf("%f %f\n",(e*c-f*b)/(e*a-b*d),(a*f-c*d)/(a*e-b*d))));return 0;}
      |                                                                               ^~~
main.c:1:79: note: 'EOF' is defined in header '<stdio.h>'; this is probably fixable by adding '#include <stdio.h>'
main.c:1:79: note: each undeclared identifier is reported only once for each function it appears in
main.c:1:83: error: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
    1 | main ()double a,b,c,d,e,f;{for(;scanf("%f %f %f %f %f %F",&a,&b,&c,&d,&e,&f)!=EOF;printf("%f %f\n",(e*c-f*b)/(e*a-b*d),(a*f-c*d)/(a*e-b*d))));return 0;}
      |                                                                                   ^~~~~~
main.c:1:83: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:1:83: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
main.c:1:83: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:1:141: error: expected statement before ')' token
    1 | main ()double a,b,c,d,e,f;{for(;scanf("%f %f %f %f %f %F",&a,&b,&c,&d,&e,&f)!=EOF;printf("%f %f\n",(e*c-f*b)/(e*a-b*d),(a*f-c*d)/(a*e-b*d))));return 0;}
      |                                                                                                                                             ^