An Introduction to C++ Getline with Syntax And Examples

What is C++ Getline?

The C++ getline() is an in-built function defined in the <string.h> header file that allows accepting and reading single and multiple line strings from the input stream. In C++, the cin object also allows input from the user, but not multi-word or multi-line input. That’s where the getline() function comes in handy. 

The function continues accepting inputs and appending them to the string until it encounters a delimiting character. Thus, you can use it to keep adding inputs for longer strings. Some primary applications include:

• Taking full name
• Taking details such as address and bio
• Asking for any long-form or multi-line input

What is the Syntax of Getline in C++?

There are two different ways of declaring and initializing the C++ getline: three parameters and two parameters. The syntax for declaring the function with three parameters is:

istream& getline (istream& is, string& str, char delimiting);

In the above syntax, istream& getline is to define the function, and the three parameters are:

• istream& is: This is the istream class’s object to define the location, to read the input stream.
• istream& str: This is the object where the string is stored after reading.
• char delimiting: This is the delimiting character that marks the end of taking inputs.

The second method of declaring the C++ getline() function with two parameters is:

istream& getline( istream& is, string& str );

In the above syntax, istream& getline is to define the function, and the three parameters are:

• istream& is: This is an istream class’s object to specify the location to read the input stream.
• istream& str: This is the object where the string is stored after reading.

Return Value

Regardless of the syntax, the getline() function returns the input stream that you pass as an argument to the function.

C++ Getline Examples to Understand How it Works

To understand the C++ getline() function, you will take the user’s name as the input and display a greeting along with the name. You will start by using the cin object and not the getline() function, for better understanding. You will later use the function to see the difference between the two.

Example: Using cin Object

#include <iostream>

#include<string.h>

using namespace std;

int main(){

    string user_name; // declaring variable   

    // taking user input with cin

    std::cout << "What is your name? :" << std::endl;

    cin>>user_name;  

    // printing the greeting

    cout<<"\nWelcome to Simplilearn "<<user_name;

    return 0;

}

Output:

As you can see in the output, only the first name of the user was displayed. That’s because the compiler stopped reading the input stream as soon as it encountered a space (“ ”) character. Thus, you can conclude that the cin object cannot read multi-word or multi-line input. That’s why you need to use the getline function.

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Example: Using C++ Getline with Two Parameters

Let’s use the C++ getline() function to greet the user from the above example using his complete name. For this example, you will use the getline() function with two parameters. This means you will not be passing the delimiting character. Let’s see it in action.

#include <iostream>

#include<string.h>

using namespace std;

int main(){

    string user_name; // declaring variable

    // taking user input with cin

    std::cout << "What is your name? :" << std::endl; 

    // using getline

    getline(cin, user_name);

    cout<<"\nWelcome to Simplilearn "<<user_name;

    return 0;

}

Output:

This time you get both David and Morrison in the output. It means that the C++ getline() function can continue reading the input stream even after encountering a space character.

Example: Using C++ Getline With Three Parameters

You can also use a delimiting character to stop the getline() function from reading the input stream after it encounters that character. To see that in action, you will use the space (“ ”) as a delimiting character to prevent the function from reading the last name after space. Thus, it will give the same output as the one where you used the cin object.

#include <iostream>

#include<string.h>

using namespace std;

int main(){

    string user_name; // declaring variable   

    // taking user input with cin

    std::cout << "What is your name? :" << std::endl;

        // using getline

    getline(cin, user_name, ' ');

    cout<<"\nWelcome to Simplilearn "<<user_name;

    return 0;

}

Output:

As you can see, although you are using the getline() function, the output displayed only the first name as used space is a delimiting character.

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How to Use C++ Getline for Character Array

You can also use C++ getline() function for a character array. However, the syntax differs from what you have seen for the strings. The syntax to use getline character array is:

istream& getline(char* , int size);

In the above syntax:

• char: This is the character pointer that points to the array.
• int size: This defines the maximum size of the array. Thus, it acts as the delimiter, since exceeding the limit will stop the reading.

Example: Getline Character Array Use

#include <iostream>

#include<string.h>

using namespace std;

int main(){  

    char cars[50]; // array declaration

    cout<< "Enter the name of some cars: ";   

    // using getline function

    cin.getline(cars, 50);

    std::cout << "\nCars list :"<<cars << std::endl;

    return 0;

}

Output:

Example: C++ Getline for Character Array and Exceeding Char Limit

In this example, you will intentionally exceed the char limit to see how the C++ getline() function reacts and stops reading the input stream.

#include <iostream>

#include<string.h>

using namespace std;

int main(){  

    char cars[50]; // array declaration

    cout<< "Enter the name of some cars: ";  

    // using getline function

    cin.getline(cars, 50);

    std::cout << "\nCars list :"<<cars << std::endl;

    return 0;

}

Output:

As you can see in the output, the getline() function stopped reading the input stream as soon as the character limit, set to 30, was reached.

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Conclusion

In this article, you learned about the C++ getline() function. You have also seen its use for character array, along with examples. You can now use it to get long-form multi-line inputs from the users quickly. Knowing about and using the C++ getline is a fundamental concept in this programming language. If you are keen to learn more about such basic concepts, you can refer to Simplilearn’s C++ Tutorial for Beginners. The tutorial covers essential concepts like C++ array and C++ for loop. With the basics clear, you can proceed with the advanced concepts to excel in C++ development. Also, learn how to write the Hello World program in C++ in our next tutorial.

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