Determines the closest number to the users input that is a perfect square.

PerfectSquare.c

/** Write a program that prompts the user for a positive integer
 * and then reports the closest integer having a whole number square root.
 * For example if the user enters 8 then the program reports 9.
 * The program should work for any number having one to seven digits.
 */

#include <stdio.h>

/* Checks to see if the number is a perfect square.
	returns 1 for yes, 0 for no. */
int PerfectSquare(int number)
{
	int x;

	for (x = 1; x*x <= number; ++x)
		if (x*x == number)
			return 1;

	return 0;
}

int main()
{
	/* The number the user inputs */
	unsigned int user_number;

	printf("Enter a number between 1 and 9999999: ");
	scanf("%d", &user_number);

	/* Checks to make sure it's a valid number. */
	if (user_number > 9999999 || user_number < 1)
	{
		printf("Please choose a number between 1 and 999999\r\n");
		return 1;
	}

	/* If the given number is a perfect square. */
	if (PerfectSquare(user_number) == 1)
	{
		printf("Your number was a perfect square!\r\n");
		return 0;
	}

	unsigned int x, y, up_counter, down_counter, closest;

	/* Loops until we find a perfect square above user_number */
	for (x = user_number+1, y = 0, up_counter = 0; y != 1; ++x, ++up_counter)
		y = PerfectSquare(x);

	/* Loops until we find a perfect square below user_number */
	for (x = user_number-1, y = 0, down_counter = 0; y != 1; --x, ++down_counter)
		y = PerfectSquare(x);

	/* Compare the two found numbers */
	if (up_counter < down_counter)
		closest = user_number+up_counter;
	else if (up_counter > down_counter)
		closest = user_number-down_counter;

	printf("Closest number with a perfect square is: %d\r\n", closest);

	return 0;
}