drawCircle.cpp

#include <iostream>
#include <math.h>
using namespace std;

int main()
{
	int r = 20;
	for (int z = 0; z <= 2 * r; z += 2) {

		int x = (int)round(r - sqrt(r * r - (r - z) * (r - z)));

		int l = 2 * (r - x);
		for (int i = 0; i <= x; i++) {
			printf(" ");
		}
		printf("*");

		for (int i = 0; i < l; i++) {
			printf(" ");
		}
		printf("*");
		printf("\r\n");
	}
}