PHP substr() function string interception usage example explanation

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Release: 2023-03-13 15:26:01
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substr() Function Returns part of string. Returns the extracted part of the string, returns FALSE if it fails, or returns an empty string.

Note: If the start parameter is a negative number and length is less than or equal to start, then length is 0.

The substr function in PHP is defined as follows:

substr(string,start,length)
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The parameter description is as follows:

ParameterDescription
stringRequired. Specifies a part of the string to be returned.
start

Required. Specifies where in the string to begin.

  • Positive numbers - start at the specified position in the string

  • Negative numbers - start at the specified position from the end of the string

  • 0 - Starts at the first character in the string

length

Optional. Specifies the length of the returned string. The default is until the end of the string.

  • Positive number - the length returned from the position of the start parameter

  • Negative number - the length returned from the end of the string Length

##The sample code is as follows:

<?php
 echo substr("Welcome to www.jb51.net!",0); //原样输出,不截取
 echo "<br>";
 echo substr("Welcome to www.jb51.net!",4,14); //从第4个字符开始连续截取14个字符
 echo "<br>";
 echo substr("Welcome to www.jb51.net!",-4,4); //从倒数第4个开始截取4个字符
 echo "<br>";
 echo substr("Welcome to www.jb51.net!",0,-4); //从第一个字符开始截取,截取到倒数第4个字符
?>
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The running result is as follows:

Welcome to www.jb51.net!
ome to www.jb5
net!
Welcome to www.jb51.
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