01 #include<stdio.h>
02 
03 int hcf(int,int);
04 
05 int main()
06 {
07 
08     int x,y=-1;
09 
10     printf("Enter numbers to find HCF/GCD (press 0 to exit) : ");
11 
12     while(1)
13     {
14         scanf("%d",&x);
15 
16         if(x<1)
17             break;
18         else if(y==-1)
19             y=x;
20         else if (x<y)
21             y=hcf(x,y);
22         else
23             y=hcf(y,x);
24     }
25 
26     printf("HCF/GCD is %d",y);
27     return 0;
28 }
29 
30 int hcf(int x,int y)
31 {
32     int i;
33 
34     for(i=x; i>=1; i--)
35     {
36         if(x%i==0&&y%i==0)
37         {
38             break;
39         }
40     }
41     return i;
42 }

 
 OUTPUT :
 Enter numbers to find HCF/GCD (press 0 to exit) :
 
 3
 6
 9
 0
 
 HCF/GCD is 3