program_6_1.cpp

c++程序设计讲义 cppprograming 含源码

// Program 6.1: Compute area of a user-specified circle
#include <iostream>
using namespace std;
// CircleArea(): compute area of circle of radius r
float CircleArea(float r) {
    const float Pi = 3.1415;
    return Pi * r * r;
}
// main(): manage computation and display of the area of
// a user-specified circle
int main() {
    // prompt and read the radius
    float DesiredRadius;
    cout << "Circle radius (number): ";
    cin >> DesiredRadius;
    // compute the area
    float Area = CircleArea(DesiredRadius);
    cout << "Area of circle with radius "
      << DesiredRadius << " is " << Area << endl;
    // all done
    return 0;
}