为什么g ++错误消息如此令人生畏？ [英] Why are g++ error messages so daunting?

问题描述

几个月前我已经开始使用C ++了。语言本身很好，

但是我真的不喜欢的是我从

g ++获得的错误消息。


g ++错误消息通常没有帮助。


有时我只是拿错误的行号并尝试自己想出什么可能是什么？是错的。或者我只记得这个错误信息

并且已经知道：如果g ++说错误X它真的意味着错误Y.


例如，请使用以下代码：


#include< iostream>

class接口{

public：

virtual std： ：string& getText（）const = 0;

};

class实现：public Interface {

std :: string text;

public：

Implementation :: Implementation（std :: string text）：text（text）{}

std :: string& getText （）const {

返回文字;

}

};


bash-2.05b $ g ++ -c test.cpp

test.cpp：在成员函数`virtual std :: string&

Implementation :: getText（）

const''：

test.cpp：13：无法将`this-> Implementation :: text''转换为

`std :: string&''


getText（）的返回类型不能是std :: string，而是const

std :: string。但为什么g ++只是这么说呢？它可以说：可以

不返回对此的引用 - > ...来自const方法...


对于初学者，它还有一个令人生畏的错误消息是

从STL使用中填充几个屏幕

std :: vector< std :: string>测试;

std :: cout<<测试;

整个候选人都......无论如何，有26个条目的列表

不可读...应该有一个更好，更易读的方式来表示

错误。


Markus

I have started with C++ a few months ago. The language itself is nice,
but what I really don''t like are the error messages that I get from
g++.

g++ error messages are often just not helpful.

Sometimes I just take the line number of the error and try to figure
out myself what might be wrong. Or I just remember this error message
and know already: if g++ says error X it really means error Y.

For example, take the following code:

#include <iostream>
class Interface{
public:
virtual std::string &getText() const = 0;
};
class Implementation : public Interface{
std::string text;
public:
Implementation::Implementation(std::string text):text(text){}
std::string &getText() const{
return text;
}
};

bash-2.05b$ g++ -c test.cpp
test.cpp: In member function `virtual std::string&
Implementation::getText()
const'':
test.cpp:13: could not convert `this->Implementation::text'' to
`std::string&''

The return type of getText() must not be std::string, but const
std::string. But why doesn''t g++ just say that? It could say: "Could
not return reference to this->... from a const method"...

For beginners, it''s also intimidating to get an error message that
fills several screens from the STL usage
std::vector<std::string> test;
std::cout << test;
The whole "candidates are..." list with 26 entries is anyway
unreadable... There should be a better, more readable way to indicate
an error.

Markus

推荐答案

g ++ -c test.cpp

test.cpp：在成员函数`virtual std :: string&

Implementation :: getText（）

const''：

test.cpp：13：无法转换`this->实现:: text''到

`std :: string&''


getText（）的返回类型不能是std :: string，但是const

std :: string。但为什么g ++只是这么说呢？它可以说：可以

不返回对此的引用 - > ...来自const方法...


对于初学者，它还有一个令人生畏的错误消息是

从STL使用中填充几个屏幕

std :: vector< std :: string>测试;

std :: cout<<测试;

整个候选人都......无论如何，有26个条目的列表

不可读...应该有一个更好，更易读的方式来表示

错误。


Markus

g++ -c test.cpp
test.cpp: In member function `virtual std::string&
Implementation::getText()
const'':
test.cpp:13: could not convert `this->Implementation::text'' to
`std::string&''

The return type of getText() must not be std::string, but const
std::string. But why doesn''t g++ just say that? It could say: "Could
not return reference to this->... from a const method"...

For beginners, it''s also intimidating to get an error message that
fills several screens from the STL usage
std::vector<std::string> test;
std::cout << test;
The whole "candidates are..." list with 26 entries is anyway
unreadable... There should be a better, more readable way to indicate
an error.

Markus

Markus Dehmann写道：

Markus Dehmann wrote:

我几个月前开始使用C ++。
语言本身很好，但我真的不喜欢
是我从g ++得到的错误消息。

g ++错误消息通常没有帮助。
有时我只是拿错误的行号
并试着找出自己可能出错的地方。
或者我只记得这条错误信息并且已经知道了：
如果是g ++说错误X它确实意味着错误Y.

例如，请使用以下代码：

#include< iostream>
类接口{
public：
virtual std :: string& getText（void）const = 0;
};
class实现：public接口{
private：std :: string text;
public：
Implementation（std :: string text）：text（text）{}
virtual std :: string& getText（void）const {
返回文字;
}
};

bash-2.05b

I have started with C++ a few months ago.
The language itself is nice, but what I really don''t like
are the error messages that I get from g++.

g++ error messages are often just not helpful. Sometimes I just take the line number of the error
and try to figure out myself what might be wrong.
Or I just remember this error message and know already:
if g++ says error X it really means error Y.

For example, take the following code:

#include <iostream>
class Interface {
public:
virtual std::string& getText(void) const = 0;
}; class Implementation: public Interface { private: std::string text;
public:
Implementation(std::string text):text(text) { } virtual std::string& getText(void) const {
return text;
}
};

bash-2.05b

g ++ -c test.cpp
test.cpp：在成员函数`virtual std :: string&
Implementation :: getText（）
const''：
test.cpp：13：could不将`this-> Implementation :: text''\
转换为`std :: string&''

getText（）的返回类型不能是std :: string但是
const std :: string。但为什么g ++只是这么说呢？它可以说：
无法返回对此的引用 - >来自... const方法...

对于初学者来说，获得一个也是令人生畏的从STL用法填充多个屏幕的错误消息
std :: vector< std :: string>测试;
std :: cout<<测试;
整个候选人......无论如何，有26个条目的列表是不可读的......
应该有一个更好，更易读的方式来指示错误。


cat test.cpp
#include< iostream>

class Interface {

public：

虚拟

std :: string& getText（void）const = 0;

};


class实现：public Interface {

private：

std :: string text;

public：

实现（std :: string text）：text（text）{}

virtual

std :: string& getText（void）const {

返回文字;

}

};

g ++ -Wall -ansi -pedantic -c test.cpp
test.cpp：8：警告：`class Implementation''\

有虚函数但非虚析构函数

test.cpp：在成员函数中\

`virtual std :: string& Implementation :: getText（）const''：

test.cpp：15：错误：无效初始化引用\

类型''std :: string&' 'from expression \

类型''const std :: string''g ++ --version

g++ -c test.cpp
test.cpp: In member function `virtual std::string&
Implementation::getText()
const'':
test.cpp:13: could not convert `this->Implementation::text'' \
to `std::string&''

The return type of getText() must not be std::string but
const std::string. But why doesn''t g++ just say that? It could say:
"Could not return reference to this->... from a const method"...

For beginners, it''s also intimidating to get an error message that
fills several screens from the STL usage
std::vector<std::string> test;
std::cout << test;
The whole "candidates are..." list with 26 entries is anyway
unreadable...
There should be a better, more readable way to indicate an error.
cat test.cpp #include <iostream>
class Interface {
public:
virtual
std::string& getText(void) const = 0;
};

class Implementation: public Interface {
private:
std::string text;
public:
Implementation(std::string text): text(text) { }
virtual
std::string &getText(void) const {
return text;
}
};
g++ -Wall -ansi -pedantic -c test.cpp test.cpp:8: warning: `class Implementation'' \
has virtual functions but non-virtual destructor
test.cpp: In member function \
`virtual std::string& Implementation::getText() const'':
test.cpp:15: error: invalid initialization of reference \
of type ''std::string&'' from expression \
of type ''const std::string'' g++ --version

g ++（GCC）3.3.3 20040412（红色Hat Linux 3.3.3-7）


尝试gnu.g ++。帮助新闻组。

另外，尝试比较GNU C ++诊断消息

带有其他编译器生成的诊断消息。

我认为你会发现它们比较有利。

编译器诊断不要期望太多。

编译器无法知道你打算写什么*

它没有拿起理解来自评论

或您选择的类型和变量名称。

诊断几乎受限于规则

的C ++计算机编程语言

，不幸的是，并不总是帮助你理解

你做错了什么。

g++ (GCC) 3.3.3 20040412 (Red Hat Linux 3.3.3-7)

Try the gnu.g++.help newsgroup.
Also, try comparing the GNU C++ diagnostic messages
with the diagnostic messages produced by other compilers.
I think that you will find that they compare favorably.
Don''t expect too much from compiler diagnostics.
The compiler can''t know what you *intended* to write.
It doesn''t pick up "understanding" from comments
or your choice to type and variable names.
Diagnostics are pretty much constrained to the rules
of the C++ computer programming language
which, unfortunately, don''t always help you understand
what you did wrong.

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