Maps in C++

Map Data Structure

Maps are made up of key-value pairs. The key acts as an identifier for the value, and both can be of any data type. Although databases are not usually built using maps, they are a good representation of maps because there is an ID (the key) and attributes (values) that correspond to it. Similar to indexing an array, It is easy to find values in a Map because as long as you have a record of the key, you have the values. This is why Maps are also called Associative Arrays. Instead of knowing an index number you can use a name, for example, to find data.

C++ has its own Map library that we will use. For the key and value we will use a pair and then put the it inside the Map so the values are mapped together.

using namespace std;

#include <map>

#include <iostream>

#include <utility>

Since C++ already has a Map library, all of the code is done in the main function.

For practice, other functions could be made that locally use a Map

This code maps famous NBA players to their ages

int main() {

map <string, int> m;

pair<string, int> first("Michael Jordan", 57);

pair<string, int> second("Larry Bird", 64);

pair<string, int> third("Earvin Johnson", 61);

pair<string, int> fourth("Isiah Thomas", 59);

m.insert(first);

m.insert(second);

m.insert(third);

m.insert(fourth);

cout << "Finding Michael Jordan's age by mapping his name: \n";

cout << m.at("Michael Jordan");

cout << "\nMapping other player's names and ages: ";

for (auto& element : m) {

cout << "\n" << element.first << ", " << element.second;

}

Output:

Finding Michael Jordan's age by mapping his name:

Mapping other player's names and ages:

Earvin Johnson, 61

Isiah Thomas, 59

Larry Bird, 64

Michael Jordan, 57

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