circle.c

it can help you know C++ souce program quckily

#include <stdio.h>
#include "data.h"			/* 在源文件中包含头文件data.h */

int main()
{
	float	area, m;
	printf("请输入圆的半径：\n");
	scanf("%f",&m);
	area=S(m);
	printf("圆面积S=%f\n", area);
	
	return 0;
}