#include <stdio.h>
#include <string.h>

size_t mylen(const char* s)
{
    int cnt = 0;
    int idx = 0;
    while (s[idx] != ‘\0‘ ){
        idx++;
        cnt++;
    }
    return cnt;
}

int main(int argc, char const *argv[])
{
    char line[] = "HELLO";
    printf("strlen=%lu\n", mylen(line));
    
    return 0;
    
}

char* mycpy(char* dst, const char* src)
{
    char* ret = dst;
    while(*src != ‘\0‘){
        *dst++ = *src++;
    }
    *dst =‘\0‘;
    
    return rest;
}