How to compare strings using PHP operator==_PHP Tutorial

The output result of the above code is:

bool(true) Therefore, when comparing strings, it is recommended to use the PHP operator == to compare strings Check strictly, or use functions such as strcmp() to avoid possible problems.

In addition, the commonly used in_array() function also has weak type problems, see the following code:

<ol class="dp-xml"><li class="alt"><span><span class="tag"><</span><span> ?php  </span></span></li><li><span>var_dump(in_array('01', array('1')));  </span></li><li class="alt"><span class="tag">?></span><span> </span></span></li></ol>

The output result of the above code is:

bool(true)

I believe that PHP programmers who have used this function for security checks know what kind of security problems this will cause, right? Fortunately, the in_array() function provides us with a third parameter. Setting it to true can turn on the mandatory type checking mechanism of the in_array() function, as shown in the following code:

<ol class="dp-xml"><li class="alt"><span><span class="tag"><</span><span> ?php   </span></span></li><li><span>var_dump(in_array('01', array('1'), true));   </span></li><li class="alt"><span class="tag">?></span><span> </span></span></li></ol>

The output result is:

bool(false)

Since PHP is a weakly typed language, that is to say, the concept of data type is weakened in PHP. Therefore, if you ignore data types too much when programming (which is also a common problem among most PHP programmers), some problems will occur and even security vulnerabilities will occur. At the end of the introduction of the PHP operator ==, there is still the annoying and annoying sentence, strict inspection and filtering of external data.

http://www.bkjia.com/PHPjc/446284.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/446284.htmlTechArticleThe output result of the above code is: bool(true) Therefore, when comparing strings, it is recommended to use PHP Operator == does a strict check on the string, or use functions like strcmp(), from...