There are many ways to find the H.C.F of two numbers in C programming. All codes below will take two integers from user and displays the H.C.F of those two integers.
C program to find HCF of two numbers
Program 1.
#include <stdio.h>
int main()
{
int num1, num2, i, hcf;
printf("Enter two integers: ");
scanf("%d %d", &num1, &num2);
for(i=1; i<=num1 || i<=num2; ++i)
{
if(num1%i==0 && num2%i==0) /* Checking whether i is a factor of both number */
hcf=i;
}
printf("H.C.F of %d and %d is %d", num1, num2, hcf);
return 0;
}
Output:
Enter two integers : 45 18
H.C.F of 45 and 18 is 9
Explanation
In this program, two integers are taken from user and stored in variable num1 and num2. Then i is initialized to 1 and for loop is executed until i becomes equal to smallest of two numbers. In each looping iteration, it is checked whether i is factor of both numbers or not. If i is factor of both numbers, it is stored to hcf. When for loop is completed, the H.C.F of those two numbers will be stored in variable hcf.
Program 2
#include <stdio.h>
int main()
{
int num1, num2, min,i;
printf("Enter two integers: ");
scanf("%d %d", &num1, &num2);
min=(num1>num2)?num2:num1; /* minimum value is stored in variable min */
for(i=min;i>=1;--i)
{
if(num1%i==0 && num2%i==0)
{
printf("HCF of %d and %d is %d", num1, num2,i);
break;
}
}
return 0;
}
Output:
Enter two integers : 55 12
H.C.F of 55 and 12 is 1
Explanation
This program is little optimized than the program above to find H.C.F. In this program, smallest of two integers entered by user is stored in variable min. Then i is initialized to min and for loop is executed. In each looping iteration, whether i is factor of these two numbers is checked. If i is a factor of these two numbers then, i will be the highest common divisor and loop is terminated using break statement.
