blocks|key|1294519|text|你可以返回一个有多个错误字段的对象，也可以使用‘out’参数。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1294520|如何做到这一点取决于你的设计，以及你到底想要返回什么。一种常见的场景是，当您需要报告状态代码以及各种类型的消息时。这有时是这样做的，函数返回状态代码作为返回值，然后通过'out‘参数返回消息状态。|1294521|如果你只是返回一组“代码”，那么构造一个结构类型并返回它可能更有意义。在这种情况下，我很容易将其作为输出参数传递，并让该方法在内部更新它，而不是每次都分配一个新的参数。|1294522|你打算这样做一次还是多次？|1294523|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|L|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|M|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

You can either return an object that has multiple error fields or you can use 'out'parameters.

How you do this depends on your design and what exactly you are trying to return back. A common scenario is when you need to report back a status code along with a message of sorts. This is sometimes done where the function returns the status code as the return value and then returns the message status via an 'out' parameter.

If you are simply returning a set of 'codes', it might make more sense to construct a struct type and return that. In that case, I would be prone to pass it in as an out parameter and have the method internally update it instead of allocating a new one each time. 

Are you planning on doing this once or many times?

blocks|key|4921762|text|返回两个值的最简单方法是使用std::pair<>模板：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4921763|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

The simplest way to return two values is with the std::pair&lt;> template:

blocks|key|4076478|text|您需要将它们作为输出参数返回：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4076479|+bool+function(int&+error1,+int&+error2,+stringx&+errorText,+int&+error3);|code-block|syntax|javascript|4076480|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You need to return them as output parameters:

<pre><code> bool function(int&amp; error1, int&amp; error2, stringx&amp; errorText, int&amp; error3);
</code></pre>

blocks|key|858961|text|如果您的目的是纯粹地返回错误状态，我会使用bitset。例如：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|858962|const+bitset<10>+a_not_set(1);
const+bitset<10>+b_not_set(2);
const+bitset<10>+c_not_set(4);

...

bitset<10>+foo(T&+a,+T&+b,+T&+c,+...)
{

++++bitset<10>+error_code+=+0;

++++...


++++if+(+/*+a+can't+be+set+*/+)
++++{
++++++++error_code+%7C=+a_not_set;
++++}

++++...

++++if+(+/*+b+can't+be+set+*/+)
++++{
++++++++error_code+%7C=+b_not_set;
++++}

++++...

++++//+etc+etc

++++return+error_code;
}

bitset<10>+err+=+foo(a,+b,+c,+...+);
if+(err+&&+a_not_set)
{
+++//+Blah.
}|code-block|syntax|javascript|858963|entityMap|0|LINK|mutability|MUTABLE|url|http://www.cppreference.com/wiki/stl/bitset/start^0|L|6|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

I would use a <a href="http://www.cppreference.com/wiki/stl/bitset/start" rel="nofollow noreferrer">bitset</a> if you're intention is to purely return error states. e.g.

<pre><code>const bitset&lt;10&gt; a_not_set(1);
const bitset&lt;10&gt; b_not_set(2);
const bitset&lt;10&gt; c_not_set(4);

...

bitset&lt;10&gt; foo(T&amp; a, T&amp; b, T&amp; c, ...)
{

 bitset&lt;10&gt; error_code = 0;

 ...


 if ( /* a can't be set */ )
 {
 error_code |= a_not_set;
 }

 ...

 if ( /* b can't be set */ )
 {
 error_code |= b_not_set;
 }

 ...

 // etc etc

 return error_code;
}

bitset&lt;10&gt; err = foo(a, b, c, ... );
if (err &amp;&amp; a_not_set)
{
 // Blah.
}
</code></pre>

blocks|key|4921824|text|您可以使用位操作(也称为标志)的整数。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4921825|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

You can use an integer with bit manipulation (aka flags).

blocks|key|4921851|text|我知道这不能真正回答你的问题，但是...|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4921852|在C%2B%2B中，您应该使用异常而不是返回错误代码。错误码是最常用的库，它们不想强制库用户使用特定的错误处理约定，但在C%2B%2B中，我们已经有了stdexcept。当然，可能有不使用异常的原因，比如编写嵌入式代码或内核扩展。|4921853|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

I know this doesn't really answer your question, but...

In C++ you should use exceptions instead of returning error codes. Error codes are most commonly used by libraries which don't want to force the library user to use a particular error handling convention, but in C++, we already have stdexcept. Of course, there might be reasons you don't use exceptions, such as if you're writing embedded code or kernel extensions.

blocks|key|859150|text|我不熟悉您的项目的内部和约束，但如果可能，请尝试使用异常而不是错误代码。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|859151|here,+at+C%2B%2B+FAQ+lite列出了原因，它们的结论是：|offset|length|859152|859153|因此，与通过返回码和if进行错误报告相比，使用try+/+catch+/+throw可能会导致代码具有更少的错误，开发成本更低，上市时间更快。|blockquote|859154|859155|entityMap|0|LINK|mutability|MUTABLE|url|http://www.parashift.com/c%2B%2B-faq-lite/exceptions.html#faq-17.1^0|0|0|L|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@$D|U|E|V|1|W]]|A|$]]|$1|F|3|-4|5|6|7|X|8|@]|9|@]|A|$]]|$1|G|3|H|5|I|7|Y|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|10|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

I am not familiar with the internals and constrains of your project, but if possible, try to use exceptions instead of error codes. 

The reasons are listed <a href="http://www.parashift.com/c++-faq-lite/exceptions.html#faq-17.1" rel="nofollow noreferrer">here, at C++ FAQ lite</a>, and they conclude with:

<blockquote>
 So compared to error reporting via return-codes and if, using try / catch / throw is likely to result in code that has fewer bugs, is less expensive to develop, and has faster time-to-market.
</blockquote>

blocks|key|4076736|text|我通常使用boost::tuple|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4076737|typedef+boost::tuple<int,int>+return_value;

return_value+r+=+my_function();

int+first_value+=+boost::get<0>(+r+);
int+second_valud+=+boost::get<1>(+r+);|code-block|syntax|javascript|4076738|编辑|4076739|您还可以使用boost::tie从元组中提取值：|4076740|boost::tie(+first_value,+second_value+)+=+r;|4076741|entityMap^0|5|C|0|0|0|6|A|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|W|8|@]|D|@]|E|$]]|$1|M|3|N|5|6|7|X|8|@$9|Y|A|Z|B|C]]|D|@]|E|$]]|$1|O|3|P|5|H|7|10|8|@]|D|@]|E|$I|J]]|$1|Q|3|-4|5|6|7|11|8|@]|D|@]|E|$]]]|R|$]]

I usually use a <code>boost::tuple</code>:

<pre><code>typedef boost::tuple&lt;int,int&gt; return_value;

return_value r = my_function();

int first_value = boost::get&lt;0&gt;( r );
int second_valud = boost::get&lt;1&gt;( r );
</code></pre>

EDIT

You can also use <code>boost::tie</code> to extract the values from a tuple:

<pre><code>boost::tie( first_value, second_value ) = r;
</code></pre>

blocks|key|859308|text|我可能会先抛出一个异常，但这取决于你的编码范例。请查阅一些书籍或文章，了解为什么c%2B%2B异常处理可能更好。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|859309|如果我真的需要使用retrun-error-code样式，我会定义一个eunm类型来指定位操作的错误。|859310|enum+error
{
+++NO_ERROR+=+0,

+++MEMBER_0_NOT_SAVED+=+1,
+++MEMBER_1_NOT_SAVED+=+1+<<+1,
+++MEMBER_2_NOT_SAVED+=+1+<<+2,
+++//+etc..

};

int+save()
{
++++int+ret+=+NO_ERROR;

++++//+fail+to+save+member_0
++++ret++%7C=+MEMBER_0_NOT_SAVED;

++++//+fail+to+save+member_1
++++ret++%7C=+MEMBER_1_NOT_SAVED;

++++//+....

++++return+ret;+
}

int+main(void)
{
++++int+ret+=+save();
++++if(+ret+==+NO_ERROR)
++++{
+++++++//+good.
++++}
++++else
++++{
++++++++if(ret+&+MEMBER_0_NOT_SAVED)
++++++++{
++++++++++++++//+do+something
++++++++}

++++++++if(ret+&+MEMBER_1_NOT_SAVED)
++++++++{
++++++++++++++//+do+something
++++++++}

++++++++//+check+the+other+errors...
++++}
}|code-block|syntax|javascript|859311|这只是一个粗略的例子。最好将其放入一个类中或使用一个名称空间。|859312|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|O|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

I probably try to throw an exception first but it depends on your coding paradigm. Please check some books or articles about reasons why c++ exception handling might be better.

If I really need to stick to retrun-error-code style, I would define a eunm type for specifying errors with bit operations..

<pre><code>enum error
{
 NO_ERROR = 0,

 MEMBER_0_NOT_SAVED = 1,
 MEMBER_1_NOT_SAVED = 1 &lt;&lt; 1,
 MEMBER_2_NOT_SAVED = 1 &lt;&lt; 2,
 // etc..

};

int save()
{
 int ret = NO_ERROR;

 // fail to save member_0
 ret |= MEMBER_0_NOT_SAVED;

 // fail to save member_1
 ret |= MEMBER_1_NOT_SAVED;

 // ....

 return ret; 
}

int main(void)
{
 int ret = save();
 if( ret == NO_ERROR)
 {
 // good.
 }
 else
 {
 if(ret &amp; MEMBER_0_NOT_SAVED)
 {
 // do something
 }

 if(ret &amp; MEMBER_1_NOT_SAVED)
 {
 // do something
 }

 // check the other errors...
 }
}
</code></pre>

This is just a rough example. It's better to put this into a class or use a namespace.

What is a good way to return success or one or more error codes from a C++ function?

I have this member function called save(), which saves to each of the member variables, there are at least ten of these member variables that are saved-to, for the call to save(), I want to find out if the call failed, and if so, on which member variable (some are hard failures, some are soft).

how to return multiple error codes from C++ function

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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从C++函数返回成功或一个或多个错误代码的好方法是什么？我有一个名为save()的成员函数，它保存到每个成员变量中，至少有十个成员变量保存到，为了调用save()，我想知道调用是否失败，如果是，哪个成员变量(一些是硬失败，一些是软失败)。

问如何从C++函数返回多个错误码
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