实现strchr

#include<stdio.h>
char* mystrchr(const char* str, char c)
{
    if (*str == NULL)
    {
        return NULL;
    }
    char* s1 = (char*)str;
    while (*s1)
    {
        if (*s1 == c)
        {
            return s1;
        }
        s1++;
    }
    return NULL;
}
int main()
{
    char* str = "abcccdef";
    char c = 'd';
    char* ret = mystrchr(str, c);
    printf("%s\n", ret);
    system("pause");
    return 0;
}