blocks|key|1791938|text|我见过的一个技巧是使用&&运算符。由于如果指针不为空，则指针“为真”，因此您可以在不更改条件的情况下执行以下操作：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1791939|assert(a+==+b+&&+"A+is+not+equal+to+B");|code-block|syntax|javascript|1791940|因为assert显示了失败的条件，所以它也会显示您的消息。如果这还不够，您可以编写自己的myAssert函数或宏，它们将显示您想要的任何内容。|1791941|entityMap^0|B|2|0|0|2|6|18|8|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|S|8|@$9|T|A|U|B|C]|$9|V|A|W|B|C]]|D|@]|E|$]]|$1|M|3|-4|5|6|7|X|8|@]|D|@]|E|$]]]|N|$]]

A hack I've seen around is to use the <code>&amp;&amp;</code> operator. Since a pointer "is true" if it's non-null, you can do the following without altering the condition:

<pre><code>assert(a == b &amp;&amp; "A is not equal to B");
</code></pre>

Since <code>assert</code> shows the condition that failed, it will display your message too. If it's not enough, you can write your own <code>myAssert</code> function or macro that will display whatever you want.

blocks|key|2005689|text|另一种选择是颠倒操作数并使用逗号运算符。您需要额外的圆括号，这样逗号就不会被视为参数之间的分隔符：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2005690|assert(("A+must+be+equal+to+B",+a+==+b));|code-block|syntax|javascript|2005691|(这是从上面的评论中复制的，为了更好的可见性)|2005692|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Another option is to reverse the operands and use the comma operator. You need extra parentheses so the comma isn't treated as a delimiter between the arguments: 

<pre><code>assert(("A must be equal to B", a == b));
</code></pre>

(this was copied from above comments, for better visibility)

blocks|key|2005747|text|BOOST_ASSERT_MSG(expre,+msg)|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|2005748|http://www.boost.org/doc/libs/1_51_0/libs/utility/assert.html|unstyled|offset|length|2005749|你可以直接使用它，或者复制Boost的代码。还请注意，Boost+assert仅用于头文件，因此如果您不想安装所有Boost，则可以只抓取该单个文件。|2005750|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|1P|0|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|S|8|@]|9|@$G|T|H|U|1|V]]|A|$]]|$1|I|3|J|5|F|7|W|8|@]|9|@]|A|$]]|$1|K|3|-4|5|F|7|X|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|E]]]]

<pre><code>BOOST_ASSERT_MSG(expre, msg)
</code></pre>

<a href="http://www.boost.org/doc/libs/1_51_0/libs/utility/assert.html">http://www.boost.org/doc/libs/1_51_0/libs/utility/assert.html</a>

You could either use that directly or copy Boost's code. Also note Boost assert is header only, so you could just grab that single file if you didn't want to install all of Boost.

blocks|key|1792233|text|由于zneak的答案在某种程度上使代码变得复杂，一种更好的方法是只注释您正在讨论的字符串文本。即：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1792234|assert(a+==+b);+//+A+must+be+equal+to+B|code-block|syntax|javascript|1792235|由于assert错误的读者无论如何都会从错误消息中查找文件和行，因此他们将在此处看到完整的解释。|1792236|因为，归根结底，这是：|1792237|assert(number_of_frames+!=+0);+//+Has+frames+to+update|1792238|读起来比这更好：|1792239|assert(number_of_frames+!=+0+&&+"Has+frames+to+update");|1792240|在代码的人工解析方面，即。可读性。也不是语言黑客。|1792241|entityMap^0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|X|8|@]|9|@]|A|$]]|$1|K|3|L|5|D|7|Y|8|@]|9|@]|A|$E|F]]|$1|M|3|N|5|6|7|Z|8|@]|9|@]|A|$]]|$1|O|3|P|5|D|7|10|8|@]|9|@]|A|$E|F]]|$1|Q|3|R|5|6|7|11|8|@]|9|@]|A|$]]|$1|S|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|T|$]]

As zneak's answer convolutes the code somewhat, a better approach is to merely comment the string text you're talking about. ie.:

<pre><code>assert(a == b); // A must be equal to B
</code></pre>

Since the reader of the assert error will look up the file and line anyway from the error message, they will see the full explanation here.

Because, at the end of the day, this:

<pre><code>assert(number_of_frames != 0); // Has frames to update
</code></pre>

reads better than this:

<pre><code>assert(number_of_frames != 0 &amp;&amp; "Has frames to update");
</code></pre>

in terms of human parsing of code ie. readability. Also not a language hack.

blocks|key|2005656|text|assert是宏/函数的组合。您可以使用__FILE__、__BASE_FILE__、__LINE__等定义您自己的宏/函数，并使用您自己的函数接收自定义消息|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2005657|entityMap^0|K|8|T|D|17|8|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]|$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|O|8|@]|D|@]|E|$]]]|G|$]]

assert is a macro/function combination. you can define your own macro/function, using <code>__FILE__</code>, <code>__BASE_FILE__</code>, <code>__LINE__</code> etc, with your own function that takes a custom message

blocks|key|2006091|text|如果断言是在类中完成的，另一种方法是使用自描述名称调用静态谓词函数。如果断言失败，消息将已经包含谓词的漂亮且自描述的名称。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2006092|例如：|2006093|static+bool+arguments_must_be_ordered(int+a,+int+b)+{return+a+<=+b;}

void+foo(int+a,+int+b)
{
++++assert(arguments_must_be_ordered(a,+b));
++++//+...
}|code-block|syntax|javascript|2006094|您甚至可能希望将该谓词函数设置为公共函数，以便类的用户可以自己验证前提条件。|2006095|即使没有为发布版本禁用assert，如果谓词相当简单，编译器也很可能会内联谓词。|offset|length|style|CODE|2006096|同样的方法也可以用于需要注释的复杂if条件。只需调用自描述谓词函数，而不是注释。|2006097|entityMap^0|0|0|0|0|B|6|0|H|2|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|V|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|W|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|X|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|Y|8|@$M|Z|N|10|O|P]]|9|@]|A|$]]|$1|Q|3|R|5|6|7|11|8|@$M|12|N|13|O|P]]|9|@]|A|$]]|$1|S|3|-4|5|6|7|14|8|@]|9|@]|A|$]]]|T|$]]

If the assert is done within a class, an alternative approach is to call a static predicate function with a self-describing name. If the assertion fails, the message will already contain the predicate's pretty and self-describing name.
E.g.:
<pre class="lang-cpp prettyprint-override"><code>static bool arguments_must_be_ordered(int a, int b) {return a &lt;= b;}

void foo(int a, int b)
{
 assert(arguments_must_be_ordered(a, b));
 // ...
}
</code></pre>
You may even want to make that predicate function public so that the class' user can verify the precondition themselves.
Even if <code>assert</code> is not disabled for release builds, the compiler will likely inline the predicate if it's fairly trivial.
The same approach can be used for complex <code>if</code> conditions needing a comment. Instead of a comment, just call a self-describing predicate function.

blocks|key|2006010|text|您也可以只编写自己的自定义断言函数。一个非常简单的例子：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2006011|bool+print_if_false(const+bool+assertion,+const+char*+msg)+{
++++if(!assertion)+{
++++++++//+endl+to+flush
++++++++std::cout+<<+msg+<<+std::endl;
++++}
++++return+assertion;
}

int+main()
{
++++int+i+=+0;
++++int+j+=+1;
++++assert(print_if_false(i+==+j,+"i+and+j+should+be+equal"));
++++return+0;
}|code-block|syntax|javascript|2006012|play+with+the+code.|offset|length|2006013|断言显示为Assertion+print_if_false(i+==+j,+"i+and+j+should+be+equal")。|style|CODE|2006014|entityMap|0|LINK|mutability|MUTABLE|url|https://godbolt.org/z/rYnvaP^0|0|0|0|J|0|0|5|1N|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Y|8|@]|9|@$I|Z|J|10|1|11]]|A|$]]|$1|K|3|L|5|6|7|12|8|@$I|13|J|14|M|N]]|9|@]|A|$]]|$1|O|3|-4|5|6|7|15|8|@]|9|@]|A|$]]]|P|$Q|$5|R|S|T|A|$U|V]]]]

You could also just write your own custom assert function. A very simple example:
<pre><code>bool print_if_false(const bool assertion, const char* msg) {
 if(!assertion) {
 // endl to flush
 std::cout &lt;&lt; msg &lt;&lt; std::endl;
 }
 return assertion;
}

int main()
{
 int i = 0;
 int j = 1;
 assert(print_if_false(i == j, &quot;i and j should be equal&quot;));
 return 0;
}
</code></pre>
<a href="https://godbolt.org/z/rYnvaP" rel="nofollow noreferrer">play with the code.</a>
The assertion reads <code>Assertion print_if_false(i == j, &quot;i and j should be equal&quot;)</code>.

blocks|key|1792155|text|对于vc，在assert.h中添加以下代码。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1792156|#define+assert2(_Expression,+_Msg)+(void)(+(!!(_Expression))+%7C%7C+(_wassert(_CRT_WIDE(#_Msg),+_CRT_WIDE(__FILE__),+__LINE__),+0)+)|code-block|syntax|javascript|1792157|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|$]]

For vc, add following code in assert.h,

<pre><code>#define assert2(_Expression, _Msg) (void)( (!!(_Expression)) || (_wassert(_CRT_WIDE(#_Msg), _CRT_WIDE(__FILE__), __LINE__), 0) )
</code></pre>

Is there a way to add or edit the message thrown by assert? I'd like to use something like 

<pre><code>assert(a == b, "A must be equal to B");
</code></pre>

Then, the compiler adds line, time and so on...

Is it possible?

Add custom messages in assert?

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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有没有办法添加或编辑assert抛出的消息？我想用像这样的东西assert(a == b, "A must be equal to B");然后，编译器添加行、时间等等……有可能吗？

问是否在断言中添加自定义消息？
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问是否在断言中添加自定义消息？
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