how to make c++ read strlen

#include <iostream>
#include <cstring>

int main() {
    char input[100]; // Assuming a maximum input length of 100 characters
    std::cout << "Enter a string: ";
    std::cin.getline(input, sizeof(input));

    std::size_t length = std::strlen(input);

    std::cout << "Length of the string: " << length << std::endl;

    return 0;
}