計算三角形面積的錯誤？

Question

我正在研究一個程序，該程序讀取三角形的三角形的底部和高度，然後報告該區域。這是我到目前爲止有：

#include<iostream> 
using namespace std; 

// a simple triangle class with a base and a height 

class Triangle { 

public:  
    double setbase(double x) { //was void but changed it to double 
     base = x; 
    }  
    double setheight(double y) { 
     height = y; 
    } 
    double getbase() { 
     return base; 
    } 
    double getheight() { 
     return height; 
    } 

private: 
    double base, height; 
};  


double area(double, double);  

int main() {  

    Triangle isoscoles1; 
    isoscoles1.setbase; 
    isoscoles1.setheight; 


    cin >> isoscoles1.setheight; 
    cin >> isoscoles1.setbase; 
    double x = isoscoles1.getbase; 
    double y = isoscoles1.getheight; 

    cout << "Triangle Area=" << area(x,y) << endl; 
    system("pause>nul"); 
} 


double area(double x, double y) { 
    double a; 
    a = (x*y)/2;  

    return a; 
} 

這是錯誤它給了我： -

Severity Code Description Project File Line Suppression State 
Error C3867 'Triangle::setbase': non-standard syntax; use '&' to create a pointer to member Project1 c:\users\ku\desktop\test\project1\main.cpp 50 
Error C3867 'Triangle::setheight': non-standard syntax; use '&' to create a pointer to member Project1 c:\users\ku\desktop\test\project1\main.cpp 51 
Error C2679 binary '>>': no operator found which takes a right-hand operand of type 'overloaded-function' (or there is no acceptable conversion) Project1 c:\users\ku\desktop\test\project1\main.cpp 54 
Error C2679 binary '>>': no operator found which takes a right-hand operand of type 'overloaded-function' (or there is no acceptable conversion) Project1 c:\users\ku\desktop\test\project1\main.cpp 55 
Error C3867 'Triangle::getbase': non-standard syntax; use '&' to create a pointer to member Project1 c:\users\ku\desktop\test\project1\main.cpp 56 
Error C3867 'Triangle::getheight': non-standard syntax; use '&' to create a pointer to member Project1 c:\users\ku\desktop\test\project1\main.cpp 57 

我在做什麼錯在這裏？

Answer 1

的問題是，在這些線路：

cin >> isoscoles1.setheight; 
cin >> isoscoles1.setbase; 

記住setheight和setbase是成員函數，而不是實際的變量。這就像寫這樣的：

void doSomething(double arg) { 
    ... 
} 

cin >> doSomething; // Error - can't read into a function! 

在上述情況下，你真的做這樣的事情：

double value; 
cin >> value; 
doSomething(value); 

這個分離出來，從調用該函數讀取值。

基於此，看看您是否可以考慮如何使用類似的解決方案來解決自己的問題。

---

這裏還有一個問題，正如評論中指出的那樣。看看這些行：

isoscoles1.setbase; 
isoscoles1.setheight; 

回想一下我們的doSomething函數。你通常會有這樣的代碼行嗎？

doSomething; 

您可以安全地刪除這兩行;他們實際上沒有做任何事情，並且導致了一些你看到的錯誤。

Answer 2

這很好。

class Triangle { public: void setbase(double x) { //was void but changed it to double base = x; }

void setheight(double y) { 
    height = y; 
} 
double getbase() { 
    return base; 
} 
double getheight() { 
    return height; 
} 

private: double base; double height; };

double area(double, double);

int main() {

Triangle isoscoles1; 
double x; 
double y; 
cin >> x >> y; 

isoscoles1.setheight(y); 
isoscoles1.setbase(x); 
double b = isoscoles1.getbase(); 
double h = isoscoles1.getheight(); 

cout << "Triangle Area=" << area(x,y) << endl; 
system("pause>nul"); 
return 0; 

}

double area(double x, double y) { double a; a = (x*y)/2;

return a; 

}