User input(cin) - Default value

Question

I can\'t figure out how to use a \"default value\" when asking the user for input. I want the user to be able to just press Enter and get the default value. Consider the fol

Answer 1

Use std::getline to read a line of text from std::cin. If the line is empty, use your default value. Otherwise, use a std::istringstream to convert the given string to a number. If this conversion fails, the default value will be used.

Here's a sample program:

#include 
#include 
#include 

using namespace std;

int main()
{
    std::cout << "Please give a number [default = 20]: ";

    int number = 20;
    std::string input;
    std::getline( std::cin, input );
    if ( !input.empty() ) {
        std::istringstream stream( input );
        stream >> number;
    }

    std::cout << number;
}