How to find the GCD of two numbers?

Question

C++ / C#

How to find the greatest common divisor of two given numbers? I wrote the code for finding a common divisor, but I can’t select the common divisor.

#include <iostream>
#include <math.h>
using namespace std;

int main()
{
    int x1,x2,k,i=1,c=1;
    setlocale(LC_ALL,"Russian");
   cout<<"Введите первое число\n";
   cin>>x1;
    cout<<"Введите второе число\n";
   cin>>x2;
   cout<<"Введите максимальное число\n";
   cin>>k;
   while(i<=k){
   if((x1%i==0 && x2%i==0) && ((x1%i==0)==(x2%i==0))){
       c=i;
        cout<<"Общий делитель -> "<<c<<endl;
      }
      i++;
   }
return 0;
}

Answer 1

Read about Euclid's algorithm