/in/foo.c: In function 'main':
/in/foo.c:44:4: warning: implicit declaration of function 'strcat' [-Wimplicit-function-declaration]
    strcat(result,tps[14-i]);
    ^~~~~~
/in/foo.c:44:4: warning: incompatible implicit declaration of built-in function 'strcat'
/in/foo.c:44:4: note: include '<string.h>' or provide a declaration of 'strcat'
/in/foo.c:47:13: warning: implicit declaration of function 'strlen' [-Wimplicit-function-declaration]
     int len=strlen(result);
             ^~~~~~
/in/foo.c:47:13: warning: incompatible implicit declaration of built-in function 'strlen'
/in/foo.c:47:13: note: include '<string.h>' or provide a declaration of 'strlen'