C Language Example - Find the Greatest Common Divisor of Two Numbers
C Language ExamplesThe user inputs two numbers, and find the greatest common divisor of these two numbers.
Example - Using for and if
#include <stdio.h>
int main()
{
int n1, n2, i, gcd;
printf("Enter two positive integers, separated by a space:");
scanf("%d %d", &n1, &n2);
for(i=1; i <= n1 && i <= n2; ++i)
{
// Determine if i is the greatest common divisor
if(n1%i==0 && n2%i==0)
gcd = i;
}
printf("The greatest common divisor of %d and %d is %d", n1, n2, gcd);
return 0;
}
Run result:
输入两个正整数，以空格分隔: 81 153 81 和 153 的最大公约数是 9
Example - Using while and if
#include <stdio.h>
int main()
{
int n1, n2;
printf("Enter two numbers, separated by a space:");
scanf("%d %d",&n1,&n2);
while(n1!=n2)
{
if(n1 > n2)
n1 -= n2;
else
n2 -= n1;
}
printf("GCD = %d",n1);
return 0;
}
Run result:
输入两个数，以空格分隔: 81 153 GCD = 9
Example - applicable to positive and negative numbers
#include <stdio.h>
int main()
{
int n1, n2;
printf("Enter two numbers, separated by a space:");
scanf("%d %d",&n1,&n2);
// If the input is a negative number, convert it to a positive number
n1 = ( n1 > 0) ? n1 : -n1;
n2 = ( n2 > 0) ? n2 : -n2;
while(n1!=n2)
{
if(n1 > n2)
n1 -= n2;
else
n2 -= n1;
}
printf("GCD = %d",n1);
return 0;
}
Run result:
输入两个数，以空格分隔: 81 -153 GCD = 9
Example - using recursion
#include <stdio.h>
int hcf(int n1, int n2);
int main()
{
int n1, n2;
printf("Enter two positive integers:");
scanf("%d %d", &n1, &n2);
printf("The greatest common divisor of %d and %d is %d", n1, n2, hcf(n1,n2));
return 0;
}
int hcf(int n1, int n2)
{
if (n2 != 0)
return hcf(n2, n1%n2);
else
return n1;
}