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#ifndef CIR_H
#define CIR_Hnamespace cir {double PI=3.141592653;//獲取圓行周長double getLenthOfCircle(double radius){return 2*PI*radius;}//獲取圓形面積double getAreaOfCircle(double radius){return PI*radius*radius;}}
#endif // CIR_H
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#include <iostream>
#include "cir.h"
using namespace std;int main()
{double myRadius = 5;cout<<"lenth:"<<cir::getLenthOfCircle(myRadius)<<endl;;cout<<"Area:"<<cir::getAreaOfCircle(myRadius)<<endl;cout << "Hello World!" << endl;return 0;
}
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