Write a Python program to find GCD of two numbers using While Loop, Functions, and Recursion. To find the GCD or HCF in Python, we have to pass at least one non-zero value

The Greatest Common Divisor (GCD) is also known as Highest Common Factor (HCF), or Greatest Common Factor (GCF), or Highest Common Divisor (HCD), or Greatest Common Measure (GCM).

In Mathematics, the Greatest Common Divisor (GCD) of two or more integers is the largest positive integer that divides given integer values without the remainder. For example, the GCD value of integer 8 and 12 is 4 because both 8 and 12 are divisible by 1, 2, and 4 (the remainder is 0), and the largest positive integer among them is 4.

## Python Program to find GCD of Two Numbers Example 1

This python program allows the user to enter two positive integer values. Next, we are using the Python While loop to restrict the i value not to exceed the user specified values.

Within Python While loop, we used the If Statement to check whether a%i and a % i remainder equals to zero or not. If true, GCD = I otherwise, skip that value.

# Python Program to find GCD of Two Numbers a = float(input(" Please Enter the First Value a: ")) b = float(input(" Please Enter the Second Value b: ")) i = 1 while(i <= a and i <= b): if(a % i == 0 and b % i == 0): gcd = i i = i + 1 print("\n HCF of {0} and {1} = {2}".format(a, b, gcd))

**OUTPUT**

## Python Program to find HCF of Two Numbers Example 2

It is another approach to find the GCD of two numbers. In this python program, we are using the Temp variable to find GCD.

# Python Program to find GCD of Two Numbers num1 = float(input(" Please Enter the First Value Num1 : ")) num2 = float(input(" Please Enter the Second Value Num2 : ")) a = num1 b = num2 while(num2 != 0): temp = num2 num2 = num1 % num2 num1 = temp gcd = num1 print("\n HCF of {0} and {1} = {2}".format(a, b, gcd))

**OUTPUT**

## Python Program to find GCD of Two Numbers without using Temp

In this program, we are finding the GCD without using the Temp variable.

# Python Program to find GCD of Two Numbers num1 = float(input(" Please Enter the First Value Num1 : ")) num2 = float(input(" Please Enter the Second Value Num2 : ")) a = num1 b = num2 if(num1 == 0): print("\n HCF of {0} and {1} = {2}".format(a, b, b)) while(num2 != 0): if(num1 > num2): num1 = num1 - num2 else: num2 = num2 - num1 gcd = num1 print("\n HCF of {0} and {1} = {2}".format(a, b, gcd))

**OUTPUT**

## Python Program to find GCD of Two Numbers using Functions

This Python program is the same as above. However, we are separating the logic using Functions

# Python Program to find GCD of Two Numbers def findgcd(num1, num2): if(num1 == 0): print("\n HCF of {0} and {1} = {2}".format(a, b, b)) while(num2 != 0): if(num1 > num2): num1 = num1 - num2 else: num2 = num2 - num1 return num1 a = float(input(" Please Enter the First Value a: ")) b = float(input(" Please Enter the Second Value b: ")) gcd = findgcd(a, b) print("\n HCF of {0} and {1} = {2}".format(a, b, gcd))

**OUTPUT**

## Python Program to Calculate GCD of Two Numbers using Recursion

It allows user to enter two positive integer values, and calculate the Greatest Common Divisor of those two values by calling findgcd function recursively.

# Python Program to find GCD of Two Numbers def findgcd(a, b): if(b == 0): return a; else: return findgcd(b, a % b) num1 = float(input(" Please Enter the First Value Num1 : ")) num2 = float(input(" Please Enter the Second Value Num2 : ")) gcd = findgcd(num1, num2) print("\n GCD of {0} and {1} = {2}".format(num1, num2, gcd))

**OUTPUT**