GCD of two numbers- how to find with programming C

Question: Write a program to find Greatest Common Divisor(GCD) of two numbers using recursion.

Explanation:

Rule 01: if(b==0) return GCD(a,b)=a;

Rule 02: else if(a>b)  return GCD(a,b)=GCD(b,a);

 Rule 03: else return GCD(a,b%a);

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Program:

<include<bits/stdc++.h>

int GCD(int,int); ///Function Prototype

int main()
{
int a,b,result;
while(scanf(“%d %d”,&a,&b)==2)
{
result=GCD(a,b); ///Function Calling
printf(“GCD of %d and %d is: %d\n”,a,b,result);
}
return 0;
}
int GCD(int p,int q) ///Function/Recursion Definition
{
if(q==0)
return p;
else if(p>q)
return GCD(q,p);
else
return GCD(p,q%p);

return -1;
}