windows - C split string function -

i trying implement function split strings, keep getting segmentation faults. working on windows xp, , therefore had implement strdup(), because windows api doesn't provide it. can tell me what's wrong following piece of code.

char** strspl(char* str, char* del) {     int size = 1;      for(int = 0; < strlen(str);) {         if(strncmp(str + i, del, strlen(del)) == 0) {             size++;             += strlen(del);         }         else {             i++;         }     }     char** res = (char**)malloc(size * sizeof(char*));     res[0] = strdup(strtok(str, del));     for(int = 0; res[i] != null; i++) {         res[i] = strdup(strtok(null, del));     }     return res; }  char* strdup(char* str) {     char* res = (char*)malloc(strlen(str));     strncpy(res, str, sizeof(str));     return res; } 

edit: using debugger found out, program crashes after following line:

res[0] = strdup(strtok(str,del)); 

also, fixed strdup(), there still no progress.

you're not counting null terminator , copying wrong number of bytes

char* strdup(char* str) {     char* res = (char*)malloc(strlen(str)); /* null terminator? */     strncpy(res, str, sizeof(str)); /* sizeof(str)                                     ** same                                     ** sizeof (char*) */     return res; }