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C++ Map

The C++ std::map is a container provided by the C++ Standard Library that allows you to store and manage a collection of key-value pairs. It is implemented as a balanced binary search tree, typically a Red-Black Tree, which ensures that the keys are stored in sorted order. Each key in the map is associated with a value, and you can use the key to look up and retrieve the corresponding value efficiently.

Here’s how to use std::map in C++:

C++
#include <iostream>
#include <map>
#include <string>

int main() {
    // Create a map with integer keys and string values
    std::map<int, std::string> myMap;

    // Insert key-value pairs into the map
    myMap[1] = "Alice";
    myMap[2] = "Bob";
    myMap[3] = "Charlie";

    // Access values using keys
    std::cout << "Value for key 2: " << myMap[2] << std::endl;

    // Check if a key exists in the map
    if (myMap.find(4) != myMap.end()) {
        std::cout << "Key 4 found in the map." << std::endl;
    } else {
        std::cout << "Key 4 not found in the map." << std::endl;
    }

    // Iterate over the map
    for (const auto& pair : myMap) {
        std::cout << "Key: " << pair.first << ", Value: " << pair.second << std::endl;
    }

    return 0;
}

In this example:

  • We include the <map> header to use std::map.
  • We create a map with integer keys and string values (std::map<int, std::string>).
  • Key-value pairs are inserted using the square bracket operator ([]).
  • We can access values in the map using keys, and we use find to check if a key exists.
  • To iterate over the map, we use a range-based for loop, which provides access to each key-value pair in the map.

std::map is a powerful and versatile data structure for maintaining collections of key-value pairs in sorted order. It’s commonly used in scenarios where you need efficient key-based lookup and automatic sorting of data.

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