please answer the following in C

The following algorithm is known as Euclids Algorithm because it appears in Euclids Elements (Book 7, ca. 300 B.C.).It may be the oldest nontrivial algorithm.

The algorithm is based on the observation that, if r is the remainder when a is divided by b, then the common divisors of a and b are the same as the common divisors of b and r. Thus we can use the equation

gcd(a, b) = gcd(b, r)

to successively reduce the problem of computing a GCD to the problem of computing the GCD of smaller and smaller pairs of integers. For example,

gcd(36, 20) = gcd(20, 16) = gcd(16, 4) = gcd(4, 0) = 4

implies that the GCD of 36 and 20 is 4. It can be shown that for any two starting numbers, this repeated reduction eventually produces a pair where the second number is 0. Then the GCD is the other number in the pair.

Write a function called gcd that takes two integer parameters and that uses Euclids algorithm to compute and return the greatest common divisor of the two numbers.