---

#include <cstring>

int my_strlen(const char* str)
{
    int len = 0;

    while (str[len] != '\0')
    {
        len++;
    }

    return len;
}

int my_strcmp(const char* str1, const char* str2)
{
    while (*str1 != '\0' && *str1 == *str2)
    {
        str1++;
        str2++;
    }

    return (unsigned char)*str1 - (unsigned char)*str2;
}

void my_strcpy(char* dest, const char* src)
{
    while (*src != '\0')
    {
        *dest = *src;
        dest++;
        src++;
    }

    *dest = '\0';
}

char* my_strcat(char* dest, const char* src)
{
    char* result = dest;

    while (*dest != '\0')
    {
        dest++;
    }

    while (*src != '\0')
    {
        *dest = *src;
        dest++;
        src++;
    }

    *dest = '\0';

    return result;
}