How to Swap Keys and Values in a Map in C++ - Step by Step Examples

How to Swap Keys and Values in a Map in C++ ?

Answer

To swap keys and values in a map in C++, you can iterate over the original map and insert each key-value pair into a new map with the value as the key and the key as the value. This method allows you to create a new map with swapped key-value pairs.

✐ Examples

1 Swapping Keys and Values in a Map of Integers

We can swap keys and values in a map of integers in C++ by iterating over the original map and inserting each key-value pair into a new map with the value as the key and the key as the value.

For example,

We start by including the necessary headers: #include <iostream> and #include <map>.
We declare and initialize a map of integers named originalMap.
We declare an empty map named swappedMap to store the swapped key-value pairs.
We iterate over the original map using a range-based for loop and insert each key-value pair into the new map with the value as the key and the key as the value.
We print the resulting map to the console to verify the swap.

C++ Program

#include <iostream>
#include <map>

int main() {
    // Declare and initialize a map of integers
    std::map<int, int> originalMap = {
        {1, 10},
        {2, 20},
        {3, 30},
        {4, 40},
        {5, 50}
    };

    // Declare an empty map to store the swapped key-value pairs
    std::map<int, int> swappedMap;

    // Iterate over the original map and insert each key-value pair into the new map with the value as the key and the key as the value
    for (const auto& pair : originalMap) {
        swappedMap[pair.second] = pair.first;
    }

    // Print the resulting map
    std::cout << "Swapped map of integers:" << std::endl;
    for (const auto& pair : swappedMap) {
        std::cout << pair.first << ": " << pair.second << std::endl;
    }

    return 0;
}

Output

Swapped map of integers:
10: 1
20: 2
30: 3
40: 4
50: 5

2 Swapping Keys and Values in a Map of Strings

We can swap keys and values in a map of strings in C++ by iterating over the original map and inserting each key-value pair into a new map with the value as the key and the key as the value.

For example,

We start by including the necessary headers: #include <iostream> and #include <map>.
We declare and initialize a map of strings named originalMap.
We declare an empty map named swappedMap to store the swapped key-value pairs.
We iterate over the original map using a range-based for loop and insert each key-value pair into the new map with the value as the key and the key as the value.
We print the resulting map to the console to verify the swap.

C++ Program

#include <iostream>
#include <map>
#include <string>

int main() {
    // Declare and initialize a map of strings
    std::map<std::string, std::string> originalMap = {
        {"one", "uno"},
        {"two", "dos"},
        {"three", "tres"},
        {"four", "cuatro"},
        {"five", "cinco"}
    };

    // Declare an empty map to store the swapped key-value pairs
    std::map<std::string, std::string> swappedMap;

    // Iterate over the original map and insert each key-value pair into the new map with the value as the key and the key as the value
    for (const auto& pair : originalMap) {
        swappedMap[pair.second] = pair.first;
    }

    // Print the resulting map
    std::cout << "Swapped map of strings:" << std::endl;
    for (const auto& pair : swappedMap) {
        std::cout << pair.first << ": " << pair.second << std::endl;
    }

    return 0;
}

Output

Swapped map of strings:
uno: one
dos: two
tres: three
cuatro: four
cinco: five

3 Swapping Keys and Values in a Map of Mixed Types

We can swap keys and values in a map with mixed key and value types in C++ by iterating over the original map and inserting each key-value pair into a new map with the value as the key and the key as the value. This example demonstrates swapping keys of type int with values of type std::string.

For example,

We start by including the necessary headers: #include <iostream> and #include <map>.
We declare and initialize a map with mixed types named originalMap.
We declare an empty map named swappedMap to store the swapped key-value pairs.
We iterate over the original map using a range-based for loop and insert each key-value pair into the new map with the value as the key and the key as the value.
We print the resulting map to the console to verify the swap.

C++ Program

#include <iostream>
#include <map>
#include <string>

int main() {
    // Declare and initialize a map with mixed types
    std::map<int, std::string> originalMap = {
        {1, "one"},
        {2, "two"},
        {3, "three"},
        {4, "four"},
        {5, "five"}
    };

    // Declare an empty map to store the swapped key-value pairs
    std::map<std::string, int> swappedMap;

    // Iterate over the original map and insert each key-value pair into the new map with the value as the key and the key as the value
    for (const auto& pair : originalMap) {
        swappedMap[pair.second] = pair.first;
    }

    // Print the resulting map
    std::cout << "Swapped map of mixed types:" << std::endl;
    for (const auto& pair : swappedMap) {
        std::cout << pair.first << ": " << pair.second << std::endl;
    }

    return 0;
}

Output

Swapped map of mixed types:
one: 1
two: 2
three: 3
four: 4
five: 5

Summary

In this tutorial, we learned How to Swap Keys and Values in a Map in C++ language with well detailed examples.

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How to Swap Keys and Values in a Map in C++ - Step by Step Examples