Updated April 1, 2023
Introduction to C++ dictionary
Dictionary type that is present in C++ is called map which acts like a container to store values that are indexed by keys that is each value in the container is associated with a key. And the type of all the values must be of the same type in a C++ map. The type of all the keys in a C++ map must be of the same type but it is not necessary that both the keys and values must be of the same type. To be able to make use of a map in C++, a map header file must be included in the C++ standard library and the values in a map can be iterated through a loop to obtain the corresponding key where each iterated item represents a key-value pair.
Syntax:
The syntax of dictionary in C++is as follows:
map<datatype_of_keys, datatype_of_values>name_of_the_map;where datatype_of_keys is the data type of the keys stored in the map, datatype_of_values is the data type of the values stored in the map and name_of_the_map represents the map name and it is a variable.
Working of dictionary in C++
Working of dictionary in C++ is as follows:
- The dictionary type that is present in C++ is called map which acts like a container to store values that are indexed by keys.
- Each value in the dictionary also called a map is associated with a key.
- The type of all the values must be of the same type in a C++ map and the type of all the keys in a C++ map must be of the same type but it is not necessary that both the keys and values must be of the same type.
- To be able to make use of a map in C++, the map header file must be included in the C++ standard library.
- The values in a map can be iterated through a loop to obtain the corresponding key where each iterated item represents a key-value pair.
Examples of C++ dictionary
Following are the examples are given below:
Example #1
C++ program to demonstrate the dictionary type map by creating a map to store key-value pairs in the map and then retrieving them:
Code:
//the headers map, string and iostream are used to be able to make use of map function, cin, cout and strings
#include <iostream>
#include <map>
#include <string>
using namespace std;
//main method is called
intmain()
{
//a map called capitalcities is created which stores keys of type strings and corresponding values of type strings
map<string, string>capitalcities;
//the elements are added to the created map
capitalcities["NewDelhi"] = "India";
capitalcities["Bangalore"] = "Karnataka";
capitalcities["Mumbai"] = "Maharashtra";
capitalcities["Chennai"] = "TamilNadu";
//iterating through the created map to print out the key and value pairs from the map
for (auto element :capitalcities)
{
//element.first represents the key in the map
cout<<element.first<<" is the capital of ";
//element.second represents the value in the map
cout<<element.second<<endl;
}
return 0;
}Output:
In the above program, map function, cin, cout functions, and strings can be used by including the headers iostream, string, and map. Then the main method is called within which a map is defined which stores the keys of type strings and their corresponding values of type string. Then the created map is iterated through a loop to retrieve the store’s key and value pairs where element. first represents the key and element. second represents the value that is printed as the output on the screen.
Example #2
C++ program to demonstrate the dictionary type map by creating a map to store key-value pairs in the map and then retrieving them:
Code:
//the headers map, string and iostream are used to be able to make use of map function, cin, cout and strings
#include <iostream>
#include <map>
#include <string>
using namespace std;
//main method is called
intmain()
{
//a map called age is created which stores keys of type strings and corresponding values of type int
map<string, int> age;
//the elements are added to the created map
age["Sanju"] = 10;
age["Ranju"] = 20;
age["Manju"] = 30;
age["Gunju"] = 40;
//iterating through the created map to print out the key and value pairs from the map
for (auto element : age)
{
//element.first represents the key in the map
cout<<element.first<<" is ";
//element.second represents the value in the map
cout<<element.second<< "years old" <<endl;
}
return 0;
}Output:
In the above program, map function, cin, cout functions, and strings can be used by including the headers iostream, string, and map. Then the main method is called within which a map is defined which stores the keys of type strings and their corresponding values of type int. Then the created map is iterated through a loop to retrieve the store’s key and value pairs where element.first represents the key and element.second represents the value that is printed as the output on the screen.
Example #3
C++ program to demonstrate the dictionary type map by creating a map to store key-value pairs in the map and then retrieving them:
Code:
//the headers map, string and iostream are used to be able to make use of map function, cin, cout and strings
#include <iostream>
#include <map>
#include <string>
using namespace std;
//main method is called
intmain()
{
//a map called patriotism is created which stores keys of type strings and corresponding values of type int
map<string, string> patriotism;
//the elements are added to the created map
patriotism["India is my motherland"] = "I love my India";
//iterating through the created map to print out the key and value pairs from the map
for (auto element : patriotism)
{
//element.first represents the key in the map
cout<<element.first<<" and ";
//element.second represents the value in the map
cout<<element.second<<endl;
}
return 0;
}Output:
In the above program, map function, cin, cout functions, and strings can be used by including the headers iostream, string, and map. Then the main method is called within which a map is defined which stores the keys of type strings and their corresponding values of type string. Then the created map is iterated through a loop to retrieve the stores key and value pairs where element.first represents the key and element.second represents the value that is printed as the output on the screen.
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This is a guide to C++ dictionary. Here we also discuss the introduction and working of dictionary in c++ along with different examples and its code implementation. You may also have a look at the following articles to learn more –
