Implementing strcpy

char *strcpy ( char *dest, const char *src );
strcpy is short for string copy, which means it copies the entire contents of src into dest. The contents of dest after strcpy will be exactly the same as src such that strcmp ( dest, src ) will return 0.

size_t strlen ( const char *s );

strlen will return the length of a string, minus the termating character ('\0'). The size_t is nothing to worry about. Just treat it as an integer that cannot be negative, which it is.