Convert N-byte string into hex

bin2hex.c

/// Convert N-byte string into hex
char* tohex(int len, const char input[len])
{
    char *buf = malloc(2 * len + 1);
    int pos = 0;
    for (const char *i = input; i < input + len; i++)
        pos += sprintf(&buf[pos], "%02x", *i);

    return buf;
}