유클리드 알고리즘을 구현하는 C 프로그램

if(firstno*secondno!=0){
   gcd=gcd_rec(firstno,secondno);
   printf("</p><p>The GCD of %d and %d is %d</p><p>",firstno,secondno,gcd);
   printf("</p><p>The LCM of %d and %d is %d</p><p>",firstno,secondno,(firstno*secondno)/gcd);
}

int gcd_rec(int x, int y){
   if (y == 0)
      return x;
   return gcd_rec(y, x % y);
}

#include<stdio.h>
int gcd_rec(int,int);
void main(){
   int firstno,secondno,gcd;
   printf("Enter the two no.s to find GCD and LCM:");
   scanf("%d%d",&firstno,&secondno);
   if(firstno*secondno!=0){
      gcd=gcd_rec(firstno,secondno);
      printf("</p><p>The GCD of %d and %d is %d</p><p>",firstno,secondno,gcd);
      printf("</p><p>The LCM of %d and %d is %d</p><p>",firstno,secondno,(firstno*secondno)/gcd);
   }
   else
      printf("One of the entered no. is zero:Quitting</p><p>");
   }
   /*Function for Euclid&#39;s Procedure*/
   int gcd_rec(int x, int y){
   if (y == 0)
      return x;
   return gcd_rec(y, x % y);
}

Enter the two no.s to find GCD and LCM:4 8

The GCD of 4 and 8 is 4

The LCM of 4 and 8 is 8