How to check if the input is a valid integer without any other chars?

Question

#include 
#include 

using namespace std;

int main()
{
    int x;
    cout << \"5 + 4 = \";
    while(!(cin >> x)){
               


        

Answer 1

You could read a string, extract an integer from it and then make sure there's nothing left:

std::string line;
std::cin >> line;
std::istringstream s(line);
int x;
if (!(s >> x)) {
  // Error, not a number
}
char c;
if (s >> c) {
  // Error, there was something past the number
}