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PHP gets string length function strlen() function

伊谢尔伦Original: 2017-04-13 09:20:2613176browse

In some website registrations or other activities, we need users to submit some information, and there will be certain requirements for this information. For example, there are some restrictions on the length of user registration information, which cannot be less than or greater than this. Here we need to use PHP's own functions to perform the acquisition operation.

The strlen() function is used to obtain the string length. Let’s talk about the syntax and application of the strlen() function.

strlen() function is mainly used to obtain the length of the specified string string.

The syntax format is as follows:

strlen(string);

Parameter: string The string whose length needs to be calculated.

Return value: Generally, the length of the string is returned. If the string is empty, the return value is 0.

Use the strlen() function to get the length of the string. The sample code is as follows:

<?php
   $str=&#39;字a符1串b长2度&#39;;  
  echo strlen($str).&#39;<br>&#39;;    //长度为19
?>

The output result is: 19

Result Analysis:

When the strlen character length is used, a UTF8 Chinese character is counted as three lengths, and numbers, English, decimal point, underline and space occupy one character, so "character a is 1 and string b is long 2 The length of "degree" is 3+1+3+1+3+1+3+1+3=19.

It should be noted that in gb2312, when strlen calculates the character length, one Chinese character only counts 2 lengths.

The strlen() function can be used to detect the length of a string in addition to obtaining the length of the string.

The following is a simple example to use the strlen() function to detect the length of the submitted user password. If the password length is less than 5, a prompt message will pop up.

The specific steps are as follows:

1. Create a new PHP file and name it index.php.

2. Add a form and set the form's action attribute to test.php.

3. Use HTML tags to design a form, add a username text box and name it user; add a password text box and name it pwd.

<html>
<body>
<form action="test.php" method="post">
   user :<input type="text" name="username"><br />
    pwd :<input type="password" name="pwd"><br />
   <input type="submit" name="submit" value="提交" />
</form>
</body>
</html>

4. In addition, create a PHP file, named test.php, and write the following code in it:

<?php
 if(strlen($_POST[&#39;pwd&#39;])<6)         //测试用户密码的长度是否小于5
 {
      // 不符合要求则弹出该信息
    echo "<script>alert(&#39;密码不能小于5位!请重新输入 &#39;);history.back();</script>";
 }
?>

In the above code, it is through the POST method (about the POST method, you can View in PHP Chinese website) Receives the user password string entered by the user. Use the strlen() function to obtain the length of the password entered by the user, and use the if conditional control statement to judge the length of the user's password. If the password entered by the user does not reach the specified length, a prompt box message will pop up.

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