How to Take std::cin Input with Spaces?

In C++, std::cin is used to accept the input from the standard input device. By default, the delimiter used by std::cin to separate input is a whitespace. In this article, we will learn how to take std::cin input with spaces in C++.

Example:

Input: Hey! Geek Welcome to GfG //input with spaces

Output: Input Entered: Hey! Geek Welcome to GfG

std::cin Input with Spaces in C++

To take std::cin input with spaces we need to customize the behavior of the standard input stream by treating the newline character (‘\n’) as a delimiter in place of a space. To achieve this use the below approach:

Approach:

• Define a custom locale facet that modifies the character classification table used by the locale to alter how characters are interpreted by the input stream.
• Inside the custom locale change the classification of the newline character ('\n') to be considered as a space character.
• Finally, apply the custom locale by using cin.imbue() to set the locale of the std::cin with a new locale.

C++ Program to Take std::cin Input with Spaces

The below program demonstrates how we can take std::cin input with spaces in C++.

C++

// C++ program to take std::cin input with spaces

#include <iostream>
#include <locale> // to work with locales
#include <string>
using namespace std;

// Defining a structure that inherits from ctype<char>
struct changeDelimiter : ctype<char> {

    // Constructor for changeDelimiter
    changeDelimiter()
        : ctype<char>(
            createTable()) // Initializing the base class
                           // ctype<char> with a table
    {
    }
    // Static function to create a table with custom
    // settings
    static mask const* createTable()
    {
        static mask
            rc[table_size]; // Creating a table with the
                            // size of the character set
        rc['\n']
            = ctype_base::space; // Set the newline
                                 // character to be treated
                                 // as whitespace
        return rc; // Return the modified table
    }
};

int main()
{
    // Creating a custom locale with the changeDelimiter
    // facet
    cin.imbue(locale(cin.getloc(), new changeDelimiter));

    // prompt the user to enter the input with spaces
    cout << "Enter Input with Spaces: " << endl;
    string inputString;

    // Read input from cin, which has the modified locale
    cin >> inputString;
    // Print the input string
    cout << "Input Entered: " << inputString << endl;
}

Output

Enter Input with Spaces: 
Hey! Geek Welcome to GfG  
Input Entered: Hey! Geek Welcome to GfG