GCD of two numbers in C

Method 1:


#include<stdio.h>
#include<conio.h>
void main()
{
int a,b,c,d,r=0,LCM,m,n;
clrscr();
printf("Enter the two numbers : ");
scanf("%d %d",&a,&b);
m=a;
n=b;
/*if(a>b)
{
c=b;
b=a;
a=c;
}
else
goto loop;
loop:
*/
do
{
r=b%a;
d=a;
a=r;
b=d;
}while(r!=0);
LCM=(m*n)/d;
printf("\n\nLCM= %d",LCM);
printf("\n\nGCD is= %d",d);
getch();
}

Method 2:

#include<stdio.h>

#include<conio.h>

void main()

{

int a,b,i=0;

clrscr();

printf("Enter the two numbers :");

scanf("%d %d",&a,&b);

if(a<b)

for(i=a;i>=1;i--)

{

if(a%i==0 && b%i==0)

{

printf(" %d ",i);

break;

}

}

if(b<a)

for(i=0;i>=1;i--)

{

if(a%i==0 && b%i==0)

{

printf(" %d ",i);

break;

}

}

getch();

}

Method 3:

#include<stdio.h>

#include<conio.h>

void main()

{

int a,b;

clrscr();

printf("Enter the two numbers: ");

scanf("%d %d",&a,&b);

m:

if(b==0)

{

printf("gcd is=%d",a);

goto n;

}

if(a>b)

{

a=a-b;

goto m;

}

else

{

b=b-a;

goto m;

}

n:

getch();

}



Method 4:

#include<stdio.h>

#include<conio.h>

int gcd(int a,int b)
{
  return (b==0)?a:gcd(b,a%b);
}
void main()

{

  int a,b;

  clrscr();

  printf("Enter the two numbers: ");

  scanf("%d %d",&a,&b);

  printf("gcd= %d ",gcd(a,b));

  getch();

}