How do I use the STL in C++?

How do I use the STL in C++?

The Standard Template Library (STL) in C++ provides a set of common classes and interfaces for data structures and algorithms. You can use it by including the appropriate headers, like <vector> for dynamic arrays or <map> for key-value pairs.

Can you give me an example of using a vector?

Sure! Here's a simple example:

#include <iostream>
#include <vector>

int main() {
    std::vector<int> numbers;
    numbers.push_back(10);
    numbers.push_back(20);
    numbers.push_back(30);

    for(int num : numbers) {
        std::cout << num << " ";
    }
    return 0;
}

This code creates a vector, adds three integers, and prints them.

What about using maps?

You can use maps to store key-value pairs. Here's an example:

#include <iostream>
#include <map>

int main() {
    std::map<std::string, int> age;
    age["Alice"] = 30;
    age["Bob"] = 25;

    for(const auto& pair : age) {
        std::cout << pair.first << " is " << pair.second << " years old." << std::endl;
    }
    return 0;
}

This code creates a map of names to ages and prints each name with its corresponding age.

Are there any performance considerations when using STL?

Yes, while STL provides convenience, it's important to consider performance. For example, vectors are efficient for random access but can be slow for insertions in the middle. Maps have logarithmic time complexity for insertions and lookups, which is generally efficient but can be slower than unordered maps for certain use cases.