Using vector (the Standard Library)

This lesson covers vector — an array whose size can freely change. It's for anyone searching "C++ vector usage."

std::vector<type> is a resizable array provided by C++'s standard library. Add an element with push_back(), and get the element count with size().

The example creates std::vector<std::string> fruits;, adds fruits with push_back(), then displays every element with a range-based for loop (for (auto& f : fruits)).

A common early mistake is being unsure when to use this versus the regular array from cpp-06. The rule of thumb: use an array when the element count is fixed ahead of time, and a vector when it might grow or shrink while the program runs.

In real projects, vector — safer and more feature-rich than a raw, C-style array — is the standard choice.

📖 Reference code

#include <iostream>
#include <vector>
#include <string>

int main() {
    std::vector<std::string> fruits;
    fruits.push_back("apple");
    fruits.push_back("orange");
    fruits.push_back("grape");
    for (auto& f : fruits) {
        std::cout << f << std::endl;
    }
    std::cout << "Count: " << fruits.size() << std::endl;
    return 0;
}

✍️ Your code

Type your code, then press "Run"

🧪 This site can't compile or run C++ directly, so it checks on the spot whether what you typed matches the reference code (scoring happens entirely in your browser — nothing is sent anywhere).