Language: C

s;main(c){for(double*q=&s,b;~scanf("%s%c",&s,&c);c&2&&printf("%f\n",*q))sscanf(&s,"%lf",q+1)-1?b=*q--,*q=s&1?s&2?s&4?*q/b:*q+b:*q-b:*q*b:*++q;}

Compiler output:
main.c:1:1: warning: data definition has no type or storage class
    1 | s;main(c){for(double*q=&s,b;~scanf("%s%c",&s,&c);c&2&&printf("%f\n",*q))sscanf(&s,"%lf",q+1)-1?b=*q--,*q=s&1?s&2?s&4?*q/b:*q+b:*q-b:*q*b:*++q;}
      | ^
main.c:1:1: error: type defaults to 'int' in declaration of 's' [-Wimplicit-int]
main.c:1:3: error: return type defaults to 'int' [-Wimplicit-int]
    1 | s;main(c){for(double*q=&s,b;~scanf("%s%c",&s,&c);c&2&&printf("%f\n",*q))sscanf(&s,"%lf",q+1)-1?b=*q--,*q=s&1?s&2?s&4?*q/b:*q+b:*q-b:*q*b:*++q;}
      |   ^~~~
main.c: In function 'main':
main.c:1:3: error: type of 'c' defaults to 'int' [-Wimplicit-int]
main.c:1:24: error: initialization of 'double *' from incompatible pointer type 'int *' [-Wincompatible-pointer-types]
    1 | s;main(c){for(double*q=&s,b;~scanf("%s%c",&s,&c);c&2&&printf("%f\n",*q))sscanf(&s,"%lf",q+1)-1?b=*q--,*q=s&1?s&2?s&4?*q/b:*q+b:*q-b:*q*b:*++q;}
      |                        ^
main.c:1:30: error: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
    1 | s;main(c){for(double*q=&s,b;~scanf("%s%c",&s,&c);c&2&&printf("%f\n",*q))sscanf(&s,"%lf",q+1)-1?b=*q--,*q=s&1?s&2?s&4?*q/b:*q+b:*q-b:*q*b:*++q;}
      |                              ^~~~~
main.c:1:1: note: include '<stdio.h>' or provide a declaration of 'scanf'
  +++ |+#include <stdio.h>
    1 | s;main(c){for(double*q=&s,b;~scanf("%s%c",&s,&c);c&2&&printf("%f\n",*q))sscanf(&s,"%lf",q+1)-1?b=*q--,*q=s&1?s&2?s&4?*q/b:*q+b:*q-b:*q*b:*++q;}
main.c:1:30: warning: incompatible implicit declaration of built-in function 'scanf' [-Wbuiltin-declaration-mismatch]
    1 | s;main(c){for(double*q=&s,b;~scanf("%s%c",&s,&c);c&2&&printf("%f\n",*q))sscanf(&s,"%lf",q+1)-1?b=*q--,*q=s&1?s&2?s&4?*q/b:*q+b:*q-b:*q*b:*++q;}
      |                              ^~~~~
main.c:1:30: note: include '<stdio.h>' or provide a declaration of 'scanf'
main.c:1:55: error: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
    1 | s;main(c){for(double*q=&s,b;~scanf("%s%c",&s,&c);c&2&&printf("%f\n",*q))sscanf(&s,"%lf",q+1)-1?b=*q--,*q=s&1?s&2?s&4?*q/b:*q+b:*q-b:*q*b:*++q;}
      |                                                       ^~~~~~
main.c:1:55: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:1:55: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
main.c:1:55: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:1:73: error: implicit declaration of function 'sscanf' [-Wimplicit-function-declaration]
    1 | s;main(c){for(double*q=&s,b;~scanf("%s%c",&s,&c);c&2&&printf("%f\n",*q))sscanf(&s,"%lf",q+1)-1?b=*q--,*q=s&1?s&2?s&4?*q/b:*q+b:*q-b:*q*b:*++q;}
      |                                                                         ^~~~~~
main.c:1:73: note: include '<stdio.h>' or provide a declaration of 'sscanf'
main.c:1:73: warning: incompatible implicit declaration of built-in function 'sscanf' [-Wbuiltin-declaration-mismatch]
main.c:1:73: note: include '<stdio.h>' or provide a declaration of 'sscanf'
main.c:1:80: error: passing argument 1 of 'sscanf' from incompatible pointer type [-Wincompatible-pointer-types]
    1 | s;main(c){for(double*q=&s,b;~scanf("%s%c",&s,&c);c&2&&printf("%f\n",*q))sscanf(&s,"%lf",q+1)-1?b=*q--,*q=s&1?s&2?s&4?*q/b:*q+b:*q-b:*q*b:*++q;}
      |                                                                                ^~
      |                                                                                |
      |                                                                                int *
main.c:1:80: note: expected 'const char *' but argument is of type 'int *'