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

bool isIntegerNumber(const std::string& string){
  std::string::const_iterator it = string.begin();
  int minSize = 0;
  if(string.size()>0 && (string[0] == '-' || string[0] == '+')){
    it++;
    minSize++;
  }
  while (it != string.end() && std::isdigit(*it)) ++it;
  return string.size()>minSize && it == string.end();
}