我有以下主要功能,使用指針創建係數的乘積。這只是項目的一小部分,用於創建多項式:C++覆蓋已定義的變量
#include "header.h"
int main()
{
TermProd x = TermProd(new Coeff(4), new Coeff(8));
x.print(); cout << endl;
x = TermProd(new Coeff(8), new Coeff(15));
x.print(); cout << endl;
return 0;
}
經過測試,覆蓋似乎正在工作。但是當我打電話給x時,出現了分段錯誤。我一直在努力並盯着它很長一段時間,但我無法弄清真正的問題。此外,我的搜索沒有導致正確的方向,所以我決定創建一個重現錯誤的小代碼片段。
我header.h文件看起來像:
class Term{
public:
Term(){};
virtual ~Term(){};
virtual Term* clone() const = 0;
virtual void print() const = 0;
};
class Coeff:public Term{
int m_val; //by def: >=0
public:
// Constructor
Coeff();
Coeff(int val = 1):m_val(val)
// Copy constructor
Coeff* clone() const{return new Coeff(this->val());}
// Destructor
~Coeff(){}
// Accessors
int val() const{return m_val;} ;
// Print
void print() const{cout << m_val; }
};
class TermProd:public Term{
TermPtr m_lhs, m_rhs;
public:
// Constructor
TermProd(TermPtr lhs, TermPtr rhs):m_lhs(lhs), m_rhs(rhs){ }
// Copy constructor
TermProd* clone() const
{
return new TermProd(m_lhs->clone(), m_rhs->clone());
}
// Destructor
~TermProd(){ delete m_lhs;delete m_rhs;}
// Accessors
Term* lhs() const { return m_lhs; }
Term* rhs() const { return m_rhs; }
// Print
void print() const
{
cout << "("; m_lhs->print(); cout << '*'; m_rhs->print(); cout << ")";
}
};
閱讀此:[規則3](http://stackoverflow.com/questions/4172722/what-is-the-rule-of -ree) – 2012-01-27 15:54:09
@Michael它會生成一個臨時對象,它將被分配給第一個對象。 – AlexTheo 2012-01-27 15:57:47