I'm new to C++ and am working through Stroustrup's Programming Principles and Practices. In section 3.3, he gives the following example:
#include <iostream>
#include <string>
int main() {
std::cout << "Please enter your first name and age\n";
std::string firstName;
int age;
std::cin >> firstName >> age;
std::cout << "Hello, " << firstName << " (age " << age << ")\n";
}
As per the text, I entered '22 Carlos' and expect the output to be 22 followed by some random number or 0. Fine, I get 0.
I then initialise the variables and input the same '22 Carlos':
string firstName = "???";
int age = -1;
I expect the output to be 'Hello, 22 (age -1)', as stated in the text, but instead get 'Hello, 22 (age 0)'. Why?
operator>>is explicitly setting invalid int input to 0. That is allowed,though the behavior was undefined prior to C++11, but is guaranteed in C++11 and later.