C++ 使用友元运算符时出现编译器错误<&书信电报;
我试图使用操作符您的C++ 使用友元运算符时出现编译器错误<&书信电报;,c++,compiler-errors,operators,operator-overloading,C++,Compiler Errors,Operators,Operator Overloading,我试图使用操作符您的friend声明位于名称空间内,但函数的定义不在名称空间内。因此,它们不匹配,并且不会激活好友权限 将定义移动到名称空间内,如 namespace long_arithm { std::ostream& operator<<(std::ostream& out, const longint& num_) { if (num_.negative()) out << '-';
friend
声明位于名称空间内,但函数的定义不在名称空间内。因此,它们不匹配,并且不会激活好友权限
将定义移动到名称空间内,如
namespace long_arithm
{
std::ostream& operator<<(std::ostream& out, const longint& num_)
{
if (num_.negative())
out << '-';
longint::const_iterator it = num_.array.end();
--it;
longint::const_iterator finish = num_.array.begin();
--finish;
while (it != finish) {
out << num_.digtochar(*it);
--it;
}
return out;
}
}
名称空间长算法
{
std::ostream&operator您的friend
声明位于命名空间内,但函数的定义不在命名空间内。因此它们不匹配,并且不会激活friend特权
将定义移动到名称空间内,如
namespace long_arithm
{
std::ostream& operator<<(std::ostream& out, const longint& num_)
{
if (num_.negative())
out << '-';
longint::const_iterator it = num_.array.end();
--it;
longint::const_iterator finish = num_.array.begin();
--finish;
while (it != finish) {
out << num_.digtochar(*it);
--it;
}
return out;
}
}
名称空间长算法
{
std::ostream&operatorIt应该可以工作。发布复制问题的最小代码。应该从函数返回out
。不能减少begin()类似的迭代器。使用reverse\u迭代器
和rbegin
/rend
代替。它应该可以工作。发布复制问题的最小代码。您应该从函数中返回out
。您不能减少begin()类似的迭代器。使用反向迭代器
和rbegin
/rend
。
../long_arithm.h:57:20: error: «std::list<signed char> long_arithm::longint::array» is private
../long_arithm.cpp:94:36: error: in this context
../long_arithm.h:57:20: error: «std::list<signed char> long_arithm::longint::array» is private
../long_arithm.cpp:96:40: error: in this context
../long_arithm.h:44:9: error: «long_arithm::schar long_arithm::longint::digtochar(long_arithm::schar) const» is protected
../long_arithm.cpp:99:28: error: in this context
// long_arithm.h
#ifndef LONG_ARITHM_H_
#define LONG_ARITHM_H_
#include <iostream>
#include <list>
namespace long_arithm {
typedef signed char schar;
class longint {
public:
typedef std::list<schar>::const_iterator const_iterator;
inline bool negative() const { return minusSign; }
friend std::ostream& operator<<(std::ostream& out, const longint& num);
enum { error_char = 127 };
protected:
schar digtochar(schar num) const;
private:
bool minusSign;
std::list<schar> array;
};
};
// long_arithm.cpp
#include "long_arithm.h"
#include <iostream>
using namespace long_arithm;
schar longint::digtochar(schar num) const {
switch (num) {
case 0: return '0';
case 1: return '1';
case 2: return '2';
case 3: return '3';
case 4: return '4';
case 5: return '5';
case 6: return '6';
case 7: return '7';
case 8: return '8';
case 9: return '9';
default: return error_char;
}
}
std::ostream& operator<<(std::ostream& out, const longint& num_) {
if (num_.negative())
out << '-';
longint::const_iterator it = num_.array.end();
--it;
longint::const_iterator finish = num_.array.begin();
--finish;
while (it != finish) {
out << num_.digtochar(*it);
--it;
}
return out;
}
namespace long_arithm
{
std::ostream& operator<<(std::ostream& out, const longint& num_)
{
if (num_.negative())
out << '-';
longint::const_iterator it = num_.array.end();
--it;
longint::const_iterator finish = num_.array.begin();
--finish;
while (it != finish) {
out << num_.digtochar(*it);
--it;
}
return out;
}
}