为什么 in_array() 使用这些(大数字)字符串错误地返回 true? [英] Why does in_array() wrongly return true with these (large numeric) strings?

问题描述

我不明白这段代码有什么问题.它正在返回找到"，它不应该.

I am not getting what is wrong with this code. It's returning "Found", which it should not.

$lead = "418176000000069007";
$diff = array("418176000000069003","418176000000057001");

if (in_array($lead,$diff))
    echo "Found";
else
    echo "Not found";

推荐答案

注意:这是 PHP 旧版本中的一个错误，在 PHP 5.4 和更新版本中已更正.

Note: This was a bug in PHP old versions and is corrected in PHP 5.4 and newer versions.

是因为PHP

这里真正的问题是因为 PHP_INT_MAX - 在我们的例子中超出了值.

The real problem here is because of the PHP_INT_MAX - the value exceeded in our case.

尝试 echo/print_r $lead 和 $diff 不使用引号.结果是

Try to echo/print_r $lead and $diff without using the quotes. It will result

$lead ---> 418176000000070000  
$diff ---> Array ( [0] => 418176000000070000 [1] => 418176000000060000 )

所以，在这种情况下，in_array 结果为真！

so, in this case, the in_array result is true!

因此在 in_array() 中使用 strict 比较，将 in_array() 中的第三个参数设置为 true

so use strict comparison in in_array() by setting third argument in in_array() as true

     if(in_array($lead,$diff,true)) //use type too
       echo "Found";
     else
       echo "Not found";
?>

试试这个.它会起作用.

Try this. It will work.

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