Check out example codes for "gcd of two numbers c++". It will help you in understanding the concepts better.

Code Example 1

// gcd function definition below:
int gcd(int a, int b) {
   if (b == 0)
   return a;
   return gcd(b, a % b);
}

int a = 105, b = 30;
cout<<"GCD of "<< a <<" and "<< b <<" is "<< gcd(a, b);
// output = "GCD of 105 and 30 is 15";

Code Example 2

int gcd(int a, int b) 
{ 
    // Everything divides 0  
    if (a == 0) 
       return b; 
    if (b == 0) 
       return a; 
    // base case 
    if (a == b) 
        return a; 
    // a is greater 
    if (a > b) 
        return gcd(a-b, b); 
    return gcd(a, b-a); 
}

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