blocks|key|3384277|text|这里的问题是你把你的表达式放在字符串中！|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3384278|您的$condition1、$condition2和$condition3变量包含字符串，而不是表达式的结果，$condition变量也是如此，它将是一个看起来像53==56%7C%7C53==57%7C%7C53==58的字符串。当PHP计算一个字符串时，如果它不为空并且不等于0，它就认为它是true，所以你的脚本将输出blah。|offset|length|style|CODE|3384279|要解决这个问题，您只需将表达式从字符串中删除即可。它应该看起来像这样：|3384280|$condition1+=+53+==+56;+//+false
$condition2+=+53+==+57;+//+false
$condition3+=+53+==+58;+//+false
$condition+=+$condition1+%7C%7C+$condition2+%7C%7C+$condition3;+//+false+%7C%7C+false+%7C%7C+false+=+false

if+($condition)+{
++++echo+'blah';
}+else+{
++++echo+'foo';+//+This+will+be+output
}|code-block|syntax|javascript|3384281|entityMap^0|0|2|B|E|B|Q|B|1J|A|29|M|3O|1|3W|4|4A|4|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@$D|S|E|T|F|G]|$D|U|E|V|F|G]|$D|W|E|X|F|G]|$D|Y|E|Z|F|G]|$D|10|E|11|F|G]|$D|12|E|13|F|G]|$D|14|E|15|F|G]|$D|16|E|17|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|18|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|19|8|@]|9|@]|A|$M|N]]|$1|O|3|-4|5|6|7|1A|8|@]|9|@]|A|$]]]|P|$]]

The problem here is that you're putting your expressions in strings!

Your <code>$condition1</code>, <code>$condition2</code>, and <code>$condition3</code> variables contain strings, and not the result of an expression, and the same goes for your <code>$condition</code> variable which will be a string that looks like <code>53==56||53==57||53==58</code>. When PHP evaluates a string it considers it <code>true</code> if it is not empty and not equal to <code>0</code>, so your script will output <code>blah</code>.

To fix this you just need to take your expressions out of the strings. It should look like this:

<pre><code>$condition1 = 53 == 56; // false
$condition2 = 53 == 57; // false
$condition3 = 53 == 58; // false
$condition = $condition1 || $condition2 || $condition3; // false || false || false = false

if ($condition) {
 echo 'blah';
} else {
 echo 'foo'; // This will be output
}
</code></pre>

blocks|key|3099141|text|您将字符串作为布尔值进行计算；它们总是为真(除了字符串""和"0"。去掉程序中几乎所有的引号。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3099142|entityMap^0|R|2|U|3|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|$]]

You're evaluating strings as booleans; they'll aways be true (except the strings <code>""</code> and <code>"0"</code>. Get rid of almost all of the quotes in your program.

blocks|key|1483318|text|这些不是条件，它们是字符串。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1483319|$condition1=53==56;
$condition2=53==57;
$condition3=53==58;
$condition=$condition1+%7C%7C+$condition2+%7C%7C+$condition3;
if($condition)
{
++++echo+"blah";
}
else
{
++++echo+"foo";
}|code-block|syntax|javascript|1483320|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|$]]

Those aren't conditions, they're strings.

<pre><code>$condition1=53==56;
$condition2=53==57;
$condition3=53==58;
$condition=$condition1 || $condition2 || $condition3;
if($condition)
{
 echo "blah";
}
else
{
 echo "foo";
}
</code></pre>

blocks|key|3384212|text|因为您没有检查这些变量，所以if+(String)将始终返回true。(除非是"")|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3384213|你应该做的是：|3384214|if(53==56+%7C%7C+53==57+%7C%7C+53==58)
{
++++echo+"blah";
}
else
{
++++echo+"foo";
}|code-block|syntax|javascript|3384215|entityMap^0|E|B|13|2|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|T|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|U|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|V|8|@]|D|@]|E|$]]]|N|$]]

Because you're not checking those variables, it's saying <code>if (String)</code> will always return true. (unless <code>""</code>)

You should be doing:

<pre><code>if(53==56 || 53==57 || 53==58)
{
 echo "blah";
}
else
{
 echo "foo";
}
</code></pre>

blocks|key|3099383|text|所有$condition*变量的计算结果都为true。PHP是这样看待它的：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3099384|if("53==56"+%7C%7C+"53==57"+%7C%7C+"53==58")|code-block|syntax|javascript|3099385|你想要的是：|3099386|$condition1+=+53==56;
$condition2+=+53==57;
$condition3+=+53==58;|3099387|entityMap^0|2|B|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|U|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|P|$]]

All <code>$condition*</code> variables will evaluate to true. This is how PHP sees it:

<pre><code>if("53==56" || "53==57" || "53==58")
</code></pre>

What you want is this:

<pre><code>$condition1 = 53==56;
$condition2 = 53==57;
$condition3 = 53==58;
</code></pre>

blocks|key|5169278|text|这是因为您正在计算一个字符串，而非空字符串的字符串的计算结果为true。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5169279|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|$]]

It's because you're evaluating a string, and strings other than empty strings evaluate to true.

blocks|key|1483400|text|你正在将一个字符串连接在一起，一个非空字符串等于php中的TRUE。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1483401|entityMap^0|T|4|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

You are concatting a string together, a non-empty string equals <code>TRUE</code> in php.

blocks|key|3099279|text|因为当if传递时，$condition是一个包含条件文本的字符串(的串联)。尝试使用if(eval($condition))。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3099280|entityMap^0|16|K|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

Because when the if passes, $condition is a string (a concatenation of) containing the text of your conditions. Try using <code>if(eval($condition))</code>.

blocks|key|3099312|text|如果字符串不为空，则始终计算为true|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3099313|和btw+php进行隐式转换为布尔值|3099314|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|$]]

String always evaluate to true if its not empty 
And btw php make implicit conversion to boolean

I am running into a funny problem with a mischievous "if" condition : 

<pre><code>$condition1="53==56";
$condition2="53==57";
$condition3="53==58";
$condition=$condition1."||".$condition2."||".$condition3;
if($condition)
{
 echo "blah";
}
else
{
 echo "foo";
}
</code></pre>

Why does the if condition pass? 
Why does php echo "blah"? What do I do to make php evaluate the "if" statement and print "foo"?

php "if" condition mystery

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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我遇到了一个恶作剧的“如果”的问题：$condition1="53==56";$condition2="53==57";$condition3="53==58";$condition=$condition1."||".$condition2."||".$condition3;if($condition){    echo "blah";}else{    echo "foo";}为什么会通过if条

问php "if“条件之谜
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