How do I count the number of standard objects in C++?

How do I count the number of standard objects in C++?

In C++, you can use the std::count algorithm from the <algorithm> header to count occurrences of a specific value in a range.

Can you show me an example of using std::count?

Sure! Here's a simple example:

#include <iostream>
#include <vector>
#include <algorithm>

int main() {
    std::vector<int> numbers = {1, 2, 3, 2, 4, 2};
    int count = std::count(numbers.begin(), numbers.end(), 2);
    std::cout << "Number of 2s: " << count << std::endl;
    return 0;
}

What if I want to count objects based on a condition?

You can use std::count_if for that. It allows you to specify a condition using a lambda function.

Can you provide an example of std::count_if?

Absolutely! Here's an example:

#include <iostream>
#include <vector>
#include <algorithm>

int main() {
    std::vector<int> numbers = {1, 2, 3, 4, 5};
    int count = std::count_if(numbers.begin(), numbers.end(), [](int n) { return n > 3; });
    std::cout << "Count of numbers greater than 3: " << count << std::endl;
    return 0;
}