strcpy vs strdup

Question

I read that strcpy is for copying a string, and strdup returns a pointer to a new string to duplicate the string.

Could you please explain

Answer 1

In the accepted answer, the implementation of strdup is presented as:

ptr2 = malloc(strlen(ptr1)+1);
strcpy(ptr2,ptr1);

However, that is somewhat sub-optimal because both strlen and strcpy need to find the length of the string by checking if each character is a \0.

Using memcpy should be more efficient:

char *strdup(const char *src) {
    size_t len = strlen(src) + 1;
    char *s = malloc(len);
    if (s == NULL)
        return NULL;
    return (char *)memcpy(s, src, len);
}