字符串替换函数

void replace_string(char * source_str,char * targ_str,char *val)
{
        char temp_sstr[4096],result[4096];
        char * p,*q;
        int len;
        len=0;
        q=p=NULL;
        memset(result,0,sizeof(result));
        memset(temp_sstr,0,sizeof(temp_sstr));
        strcpy(temp_sstr,source_str);
        p=q=temp_sstr;
        len=strlen(targ_str);
        while(q!=NULL)
        {
                if((q=strstr(p,targ_str))!=NULL)
                {
                        strncat(result,p,q-p);
                        strcat(result,val);
                        strcat(result,"\0");
                        q+=len;
                }
                else
                        strcat(result,p);
        }
        strcpy(source_str,result);

}