PHP substr() function string interception usage example explanation

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)

The parameter description is as follows:

Parameter	Description
string	Required. 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
?>

The running result is as follows:

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

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