書上面說可以在類定義外定義函數，但是小弟用VC試驗的時候 發現卻不可以程序如下：這個是書上給出的 但是運行通不過“void rectangle::assign(double len,double wide){length=len;width=wide;}”就是要定義的函數，如果將其寫在類 rectangle定義中則可以運行 程序：#include<iostream.h>class rectangle{protected:double length;double width;public:rectangle(){assign(0,0);}rectangle(double len,double wide){assign(len,wide);}double getLength(){return length;}double getWidth(){return width;}double getArea(){return length*width;}};void rectangle::assign(double len,double wide){length=len;width=wide;}main(){rectangle rect;double len,wide;cout<<"enter length of rectangle:";cin>>len;cout<<"enter width of rectangle:";cin>>wide;rect.assign(len,wide);cout<<"rectangle length="<<rect.getLength()<<"\n"<<" width ="<<rect.getWidth()<<"\n"<<" area ="<<rect.getArea()<<"\n";return 0;}
2 回答
慕神8447489
TA貢獻1780條經驗 獲得超1個贊
正確的程序為：
#include<iostream.h>
class rectangle
{
protected:
double length;
double width;
public:
rectangle::assign(double len,double wide);
rectangle(){assign(0,0);}
rectangle(double len,double wide){assign(len,wide);}
double getLength(){return length;}
double getWidth(){return width;}
double getArea(){return length*width;}
};
rectangle::assign(double len,double wide)
{
length=len;width=wide;
}
int main()
{
rectangle rect;
double len,wide;
cout<<"enter length of rectangle:";
cin>>len;
cout<<"enter width of rectangle:";
cin>>wide;
rect.assign(len,wide);
cout<<"rectangle length="<<rect.getLength()<<"\n"
<<" width ="<<rect.getWidth()<<"\n"
<<" area ="<<rect.getArea()<<"\n";
return 0;
}
在類定義外定義函數時需在類內做函數聲明。
另void rectangle::assign(double len,double wide) 類聲明重復，這里rectangle是定義的類，是你需要的，所以void不要。還有main( )前必須有類聲明，這里為int。
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