Language: C

char*p,s[9999],t[9999];c,l,i;main(n){for(;scanf("%d",&n)*n;puts(s))for(scanf("%s",s);n--;strcpy(s,t))for(c=*s,p=t,l=i=0;c;c=s[i])sprintf(p,"%d%c",++l,c),s[++i]-c?p=t+strlen(t,l=0):0;}

Compiler output:
main.c:1:24: warning: data definition has no type or storage class
    1 | char*p,s[9999],t[9999];c,l,i;main(n){for(;scanf("%d",&n)*n;puts(s))for(scanf("%s",s);n--;strcpy(s,t))for(c=*s,p=t,l=i=0;c;c=s[i])sprintf(p,"%d%c",++l,c),s[++i]-c?p=t+strlen(t,l=0):0;}
      |                        ^
main.c:1:24: error: type defaults to 'int' in declaration of 'c' [-Wimplicit-int]
main.c:1:26: error: type defaults to 'int' in declaration of 'l' [-Wimplicit-int]
    1 | char*p,s[9999],t[9999];c,l,i;main(n){for(;scanf("%d",&n)*n;puts(s))for(scanf("%s",s);n--;strcpy(s,t))for(c=*s,p=t,l=i=0;c;c=s[i])sprintf(p,"%d%c",++l,c),s[++i]-c?p=t+strlen(t,l=0):0;}
      |                          ^
main.c:1:28: error: type defaults to 'int' in declaration of 'i' [-Wimplicit-int]
    1 | char*p,s[9999],t[9999];c,l,i;main(n){for(;scanf("%d",&n)*n;puts(s))for(scanf("%s",s);n--;strcpy(s,t))for(c=*s,p=t,l=i=0;c;c=s[i])sprintf(p,"%d%c",++l,c),s[++i]-c?p=t+strlen(t,l=0):0;}
      |                            ^
main.c:1:30: error: return type defaults to 'int' [-Wimplicit-int]
    1 | char*p,s[9999],t[9999];c,l,i;main(n){for(;scanf("%d",&n)*n;puts(s))for(scanf("%s",s);n--;strcpy(s,t))for(c=*s,p=t,l=i=0;c;c=s[i])sprintf(p,"%d%c",++l,c),s[++i]-c?p=t+strlen(t,l=0):0;}
      |                              ^~~~
main.c: In function 'main':
main.c:1:30: error: type of 'n' defaults to 'int' [-Wimplicit-int]
main.c:1:43: error: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
    1 | char*p,s[9999],t[9999];c,l,i;main(n){for(;scanf("%d",&n)*n;puts(s))for(scanf("%s",s);n--;strcpy(s,t))for(c=*s,p=t,l=i=0;c;c=s[i])sprintf(p,"%d%c",++l,c),s[++i]-c?p=t+strlen(t,l=0):0;}
      |                                           ^~~~~
main.c:1:1: note: include '<stdio.h>' or provide a declaration of 'scanf'
  +++ |+#include <stdio.h>
    1 | char*p,s[9999],t[9999];c,l,i;main(n){for(;scanf("%d",&n)*n;puts(s))for(scanf("%s",s);n--;strcpy(s,t))for(c=*s,p=t,l=i=0;c;c=s[i])sprintf(p,"%d%c",++l,c),s[++i]-c?p=t+strlen(t,l=0):0;}
main.c:1:43: warning: incompatible implicit declaration of built-in function 'scanf' [-Wbuiltin-declaration-mismatch]
    1 | char*p,s[9999],t[9999];c,l,i;main(n){for(;scanf("%d",&n)*n;puts(s))for(scanf("%s",s);n--;strcpy(s,t))for(c=*s,p=t,l=i=0;c;c=s[i])sprintf(p,"%d%c",++l,c),s[++i]-c?p=t+strlen(t,l=0):0;}
      |                                           ^~~~~
main.c:1:43: note: include '<stdio.h>' or provide a declaration of 'scanf'
main.c:1:60: error: implicit declaration of function 'puts' [-Wimplicit-function-declaration]
    1 | char*p,s[9999],t[9999];c,l,i;main(n){for(;scanf("%d",&n)*n;puts(s))for(scanf("%s",s);n--;strcpy(s,t))for(c=*s,p=t,l=i=0;c;c=s[i])sprintf(p,"%d%c",++l,c),s[++i]-c?p=t+strlen(t,l=0):0;}
      |                                                            ^~~~
main.c:1:60: note: include '<stdio.h>' or provide a declaration of 'puts'
main.c:1:90: error: implicit declaration of function 'strcpy' [-Wimplicit-function-declaration]
    1 | char*p,s[9999],t[9999];c,l,i;main(n){for(;scanf("%d",&n)*n;puts(s))for(scanf("%s",s);n--;strcpy(s,t))for(c=*s,p=t,l=i=0;c;c=s[i])sprintf(p,"%d%c",++l,c),s[++i]-c?p=t+strlen(t,l=0):0;}
      |                                                                                          ^~~~~~
main.c:1:1: note: include '<string.h>' or provide a declaration of 'strcpy'
  +++ |+#include <string.h>
    1 | char*p,s[9999],t[9999];c,l,i;main(n){for(;scanf("%d",&n)*n;puts(s))for(scanf("%s",s);n--;strcpy(s,t))for(c=*s,p=t,l=i=0;c;c=s[i])sprintf(p,"%d%c",++l,c),s[++i]-c?p=t+strlen(t,l=0):0;}
main.c:1:90: warning: incompatible implicit declaration of built-in function 'strcpy' [-Wbuiltin-declaration-mismatch]
    1 | char*p,s[9999],t[9999];c,l,i;main(n){for(;scanf("%d",&n)*n;puts(s))for(scanf("%s",s);n--;strcpy(s,t))for(c=*s,p=t,l=i=0;c;c=s[i])sprintf(p,"%d%c",++l,c),s[++i]-c?p=t+strlen(t,l=0):0;}
      |                                                                                          ^~~~~~
main.c:1:90: note: include '<string.h>' or provide a declaration of 'strcpy'
main.c:1:130: error: implicit declaration of function 'sprintf' [-Wimplicit-function-declaration]
    1 | char*p,s[9999],t[9999];c,l,i;main(n){for(;scanf("%d",&n)*n;puts(s))for(scanf("%s",s);n--;strcpy(s,t))for(c=*s,p=t,l=i=0;c;c=s[i])sprintf(p,"%d%c",++l,c),s[++i]-c?p=t+strlen(t,l=0):0;}
      |                                                                                                                                  ^~~~~~~
main.c:1:130: note: include '<stdio.h>' or provide a declaration of 'sprintf'
main.c:1:130: warning: incompatible implicit declaration of built-in function 'sprintf' [-Wbuiltin-declaration-mismatch]
main.c:1:130: note: include '<stdio.h>' or provide a declaration of 'sprintf'
main.c:1:167: error: implicit declaration of function 'strlen' [-Wimplicit-function-declaration]
    1 | char*p,s[9999],t[9999];c,l,i;main(n){for(;scanf("%d",&n)*n;puts(s))for(scanf("%s",s);n--;strcpy(s,t))for(c=*s,p=t,l=i=0;c;c=s[i])sprintf(p,"%d%c",++l,c),s[++i]-c?p=t+strlen(t,l=0):0;}
      |                                                                                                                                                                       ^~~~~~
main.c:1:167: note: include '<string.h>' or provide a declaration of 'strlen'
main.c:1:167: warning: incompatible implicit declaration of built-in function 'strlen' [-Wbuiltin-declaration-mismatch]
main.c:1:167: note: include '<string.h>' or provide a declaration of 'strlen'
main.c:1:167: error: too many arguments to function 'strlen'