blocks|key|2880353|text|试着用括号想象一下：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2880354|%2B%2Ba+%7C%7C+%2B%2Bb+&&+%2B%2Bc;|code-block|syntax|javascript|2880355|等于|2880356|(%2B%2Ba)+%7C%7C+(%2B%2Bb+&&+%2B%2Bc);|2880357|它是从左到右计算的。|2880358|如果&&并具有相同的优先级，则如下所示|2880359|(%2B%2Ba+%7C%7C+%2B%2Bb)+&&+(%2B%2Bc);|2880360|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|W|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|X|8|@]|9|@]|A|$]]|$1|O|3|P|5|D|7|Y|8|@]|9|@]|A|$E|F]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

Just try to imagine it with parentheses:

<pre><code>++a || ++b &amp;&amp; ++c;
</code></pre>

equals

<pre><code>(++a) || (++b &amp;&amp; ++c);
</code></pre>

which is evaluated from left to right.

if &amp;&amp; and || would have the same precedence, it would look like

<pre><code>(++a || ++b) &amp;&amp; (++c);
</code></pre>

blocks|key|2898774|text|优先规则只说明它将按以下方式进行评估：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2898775|%2B%2Ba+%7C%7C+(%2B%2Bb+&&+%2B%2Bc);|code-block|syntax|javascript|2898776|现在出现了逻辑运算符的短路行为，它说，必须从左到右计算项，并在知道结果时停止。右边的部分永远不会被执行。|2898777|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|$]]

The precedence rules only say that it will be evaluated like this:

<pre><code>++a || (++b &amp;&amp; ++c);
</code></pre>

Now comes the short circuiting behavior of the logic operators which says that you have to evaluate terms from left to right and stop when the result is known. The part on the right never gets executed.

blocks|key|932355|text|评价的先后顺序是完全不同的两件事。对于逻辑运算符表达式，求值总是从左到右.表达式%2B%2Ba+%7C%7C+%2B%2Bb+&&+%2B%2Bc被解释为|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|932356|932357|评估%2B%2Ba|ordered-list-item|932358|，如果1的结果为0，则评估%2B%2Bb+&&+%2B%2Bc|932359|932360|表达式被解析为%2B%2Ba+%7C%7C+(%2B%2Bb+&&+%2B%2Bc)；如果子表达式%2B%2Ba或%2B%2Bb+&&+%2B%2Bc之一为真，则整个表达式为true。|932361|entityMap^0|14|H|0|0|0|0|0|7|J|X|3|11|A|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|T|8|@]|D|@]|E|$]]|$1|G|3|H|5|I|7|U|8|@]|D|@]|E|$]]|$1|J|3|K|5|I|7|V|8|@]|D|@]|E|$]]|$1|L|3|-4|5|6|7|W|8|@]|D|@]|E|$]]|$1|M|3|N|5|6|7|X|8|@$9|Y|A|Z|B|C]|$9|10|A|11|B|C]|$9|12|A|13|B|C]]|D|@]|E|$]]|$1|O|3|-4|5|6|7|14|8|@]|D|@]|E|$]]]|P|$]]

Precedence and order of evaluation are two completely different things. For logical operator expressions, evaluation is always left-to-right. The expression <code>++a || ++b &amp;&amp; ++c</code> is interpreted as

<ol>
<li>Evaluate ++a</li>
<li>If the result of 1 is zero, evaluate ++b &amp;&amp; ++c</li>
</ol>

The expression is parsed as <code>++a || (++b &amp;&amp; ++c)</code>; the whole expression is true if either of the subexpressions <code>++a</code> or <code>++b &amp;&amp; ++c</code> is true.

blocks|key|2880274|text|仅在解析树中使用&&+has+higher+precedence。但是编译器将代码优化为|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2880275|if(+!%2B%2Ba+)+{
++++%2B%2Bb+&&+%2B%2Bc;
}|code-block|syntax|javascript|2880276|entityMap^0|8|O|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

<code>&amp;&amp; has higher precedence</code> only in parse tree. But compiler optimizes the code as

<pre><code>if( !++a ) {
 ++b &amp;&amp; ++c;
}
</code></pre>

blocks|key|2880318|text|您的示例%2B%2Ba+%7C%7C+%2B%2Bb+&&+%2B%2Bc与%2B%2Ba+%7C%7C+(%2B%2Bb+&&+%2B%2Bc)相同。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2880319|entityMap^0|4|H|M|J|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|M|8|@]|D|@]|E|$]]]|G|$]]

Your example <code>++a || ++b &amp;&amp; ++c</code> is the same as <code>++a || (++b &amp;&amp; ++c)</code>.

<blockquote>
 Possible Duplicate: 
 <a href="https://stackoverflow.com/questions/3700352/why-x-y-z-calculate-x-firstly-however-operator-is-higher">why &ldquo;++x || ++y &amp;&amp; ++z&rdquo; calculate &ldquo;++x&rdquo; firstly ? however,Operator &ldquo;&amp;&amp;&rdquo; is higher than &ldquo;||&rdquo;</a> 
</blockquote>



If you look at C's precedence table, you'll see that &amp;&amp; has higher precedence than ||.

But take a look at the following code:

<pre><code>a=b=c=1;

++a || ++b &amp;&amp; ++c;

printf("%d %d %d\n",a,b,c);
</code></pre>

It prints out "2 1 1", meaning that the "++a" is evaluated first, and once the program sees a TRUE there it stops right there, because what is on the other side of the || is not important.

But since &amp;&amp; has higher precedence than ||, shouldn't "++b &amp;&amp; ++c" be evaluated first, and then the result plugged back into "++a || result" ? (in this case the program would print "1 2 2").

Precedence of Logical Operators in C

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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 可能重复：如果您查看C的优先级表，您将看到&&具有较高的优先级。但是看看下面的代码：a=b=c=1;++a || ++b && ++c;printf("%d %d %d\n",a,b,c);它打印出“21 1"，这意味着首先计算"++a”，一旦程序在那里看到一个真，它就会停在那里，因为在另一边的情况并不重要。但是，既然&&具有较高的优先级，那么不应该先计算"++b && ++c“，然后再将结果插

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