对非const的引用的初始值必须是左值 [英] initial value of reference to non-const must be an lvalue
问题描述
我需要一些帮助来澄清警告引用的初始值
到非const必须是左值。
我我正在这个小组中寻找某人有类似的情况，比如
我。我在帖子中找到了：
http://groups.google.com/group/comp....c0774eeb3bd998
// ************************************ ************** *******************
//代码
// ********************************************** **** *******************
#include< iostream.h>
class ostream; //需要重载<<
类复杂{
double re，im; //班级的私人成员
public：
complex（）{re = 0.0; IM = 0.0; } //空构造函数
complex（double r，double i = 0.0）//来自2个双精度的构造函数
{re = r; IM = I; }
朋友ostream& operator<（&ostream&，complex&）;
朋友内联复杂运算符+（复杂，复杂）;
};
inline complex operator +（complex a1，complex a2）//添加2个复数
{return complex（a1.re + a2.re，a1.im + a2.im）; }
ostream& operator<（ostream& os，complex& cnum）//输出复数
{os<< "（"<< cnum.re<<<"""<<< cnum.im<<""）" ;;返回; };
int main（无效）
{complex a（1,2），b（3,4）; //定义复数
cout<<" a =" << a<<"，b =" << b<<" a + b = << a + b<< ENDL; //打印总和
}
我的编译器也收到相同的警告。
但是我添加了一些声明：
// ************************************ ************** *******************
//代码
// ********************************************** **** *******************
int a1 = 2;
int b1 = 3;
cout<< a1 + b1;
这很顺利。
什么'这两个代码之间的区别是什么？我如何摆脱这些
警告？
谢谢
Hi,I need some help to clarify the warning "initial value of reference
to non-const must be an lvalue".
I''m searching in this groups to find someone has the same situation like
me. I found in the Post:
http://groups.google.com/group/comp....c0774eeb3bd998
//************************************************** *******************
// CODE
//************************************************** *******************
#include <iostream.h>
class ostream; //Need for Overloading <<
class complex {
double re, im; //Private members of class
public:
complex() { re=0.0; im=0.0; } //Empty Constructor
complex(double r, double i=0.0) //Constructor from 2 doubles
{ re=r; im=i; }
friend ostream& operator<<(ostream&, complex&);
friend inline complex operator+(complex, complex);
};
inline complex operator+(complex a1, complex a2) //Add 2 complex numbers
{ return complex(a1.re+a2.re, a1.im+a2.im); }
ostream& operator<<(ostream& os, complex& cnum) //Output a complex number
{ os << "(" << cnum.re << "," << cnum.im << ") "; return os; };
int main(void)
{ complex a(1,2), b(3,4); //Define complex numbers
cout <<"a=" << a <<",b=" << b <<" a+b = " << a+b << endl; //Print sum
}
I also get the same warning in my compiler.
but I add some statement like:
//************************************************** *******************
// CODE
//************************************************** *******************
int a1=2;
int b1=3;
cout<<a1+b1;
this goes very well.
What''s the difference between these two code? How can I get rid of these
warnings?
Thanks
推荐答案
On 2008-01-10 20:28:57 -0500，asm23< as ******** @ gmail.comsaid：
On 2008-01-10 20:28:57 -0500, asm23 <as********@gmail.comsaid:
>
cout<<" a =" << a<<"，b =" << b<<" a + b = << a + b<< ENDL; //打印金额
>
cout <<"a=" << a <<",b=" << b <<" a+b = " << a+b << endl; //Print sum
摆脱噪音：
Get rid of the noise:
cout<< A + B;
cout << a+b;
现在如果你得到同样的警告，你知道在哪里看。
-
Pete
Roundhouse Consulting，Ltd。（ www.versatilecoding.com ）作者
标准C ++库扩展：教程和参考
www.petebecker.com/tr1book ）
Now if you get the same warning, you know where to look.
--
Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The
Standard C++ Library Extensions: a Tutorial and Reference
(www.petebecker.com/tr1book)
Pete Becker写道：
Pete Becker wrote:
On 2008-01-10 20:28:57 -0500，asm23< as ******** @ gmail.comsaid：
On 2008-01-10 20:28:57 -0500, asm23 <as********@gmail.comsaid:
>>
cout<<" a =" << a<<"，b =" << b<<" a + b = << a + b<< ENDL; //打印金额
>>
cout <<"a=" << a <<",b=" << b <<" a+b = " << a+b << endl; //Print sum
摆脱噪音：
Get rid of the noise:
谢谢，你说我应该使用#pragma warning（disable：XXX）获取
摆脱警告？
Thanks, you say I should use the "#pragma warning (disable:XXX) to get
rid of the warnings?
>
>
> cout<< A + B;
> cout << a+b;
现在，如果你收到相同的警告，你知道在哪里看。
Now if you get the same warning, you know where to look.
On 2008-01-10 21：09：36 -0500，asm23< as ******** @ gmail.comsaid：
On 2008-01-10 21:09:36 -0500, asm23 <as********@gmail.comsaid:
Pete Becker写道：
Pete Becker wrote:
> On 2008-01-10 20:28:57 -0500，asm23< as ******** @ gmail.comsaid：
>On 2008-01-10 20:28:57 -0500, asm23 <as********@gmail.comsaid:
>>>
cout<<" a =" << a<<"，b =" << b<<" a + b = << a + b<< ENDL; //打印金额
>>>
cout <<"a=" << a <<",b=" << b <<" a+b = " << a+b << endl; //Print sum
摆脱噪音：
Get rid of the noise:
谢谢，你说我应该使用#pragma警告（禁用：XXX）获取
摆脱警告？
Thanks, you say I should use the "#pragma warning (disable:XXX) to get
rid of the warnings?
No.简化发生警告的声明。
No. Simplify the statement where the warning occurs.
>>
>>
>> cout<< A + B;
>> cout << a+b;
现在，如果你收到相同的警告，你知道在哪里看。
Now if you get the same warning, you know where to look.
-
Pete
Roundhouse Consulting，Ltd。（ www.versatilecoding.com ）作者
标准C ++库扩展：a教程和参考
（ www.petebecker.com/tr1book）
--
Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The
Standard C++ Library Extensions: a Tutorial and Reference
(www.petebecker.com/tr1book)
这篇关于对非const的引用的初始值必须是左值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
