How to compare code for efficiency

 
#define CHECK_POS_OF_SUB_STR(STR,SUBSTR)   if((p=pos(STR,SUBSTR)) >= 0 ){ \
         printf("pos of (%s) in (%s) is %d\n",SUBSTR,STR,p);\
    }\
    else if(p==-2) {\
        printf("(%s) is not a substr of  %s\n",SUBSTR,STR);\
    }\
    else {\
        printf("One of the strings is empty\n");\
    }
 char string[] = "aaabbbccdefgghijkklmnnopqrsstuvwxyyyzz";
 char substr1[]="ggghij";
 char substr2[]="ggghij";
 char substr3[]="ggghijk";
 char substr4[]="ggghijj"; 
 char substr5[]="xyyyyzzzz"
 char substr6[]="ccdex"
 char substr7[]="aaabbccdefggghijkklmnnopqrsstuvwxyyyzz";

 CHECK_POS_OF_SUB_STR(string,substr1);
 CHECK_POS_OF_SUB_STR(string,substr2);
 CHECK_POS_OF_SUB_STR(string,substr3);
 CHECK_POS_OF_SUB_STR(string,substr4);
 CHECK_POS_OF_SUB_STR(string,substr5);
 CHECK_POS_OF_SUB_STR(string,substr6);
 CHECK_POS_OF_SUB_STR(string,substr7);

int pos( char *string , char *substring)
 {
     char *sub = substring;
     char *str = string;
 
     if(!string || !substring){
         return -1;
     }
     while( *str )
     { 
         if(*str == *sub)
         {
             char *to = str;
             while(*sub && (*to == *sub))
                 to++, sub++;
             if(!*sub)
                 return str - string;//start pos of substr
         }
         str++;
         sub=substring;
     }
     return -2;// substr is not there
 }

int pos( char *str , char *sub)
{
    char *m = str;;
    char *sstr = sub;
    int cnt = 0;

    if (!str || !sub)
    {
        return -1;
    }

    while( *str )
    {
        if(*sstr && (*str != *sstr))
        {
            str++;
            if(cnt){
                sstr = sub;
                cnt = 0;
            }
        }else if(*sstr){
            str++,sstr++;
            cnt++;

        }else{
            return str - cnt - m;
        }
    }
    if ( !*str && !*sstr )
        return str- cnt - m;
    else
        return -2;
}