Talk about the correct usage of substr and substring in PHP and the introduction of related parameters _php example

We all know that the string intercept characters in JS have functions substr and substring, and PHP, PHP, there is no directly available substring function, but there are substr functions.
Don't believe you can test it. Here's a good piece of code.

< $a = "Me"; Echo (substr ($a,,));//Output me?> The following is an error code <? $a = "Me"; Echo (subString ($a,,)); >

The substr () function returns a portion of a string.

SUBSTR (String,start,length)

String: Strings to intercept

Start

Positive number-starts at the specified position in the string
Negative number-starts at the specified position from the end of the string
0-Starts at the first character in a string

Length

Optional. Specifies the length of the string to return. The default is until the end of the string.
Positive number-returns from the position where the start parameter is located
Negative-returns from the end of the string

The usage of PHP substr () is detailed

Definition and usage

The substr () function returns a portion of a string. Using the substr () function to intercept Chinese can be garbled and it is recommended to use the MB_SUBSTR () function to intercept Chinese.

Grammar

SUBSTR (String,start,length)

Parameters	Description
String	Necessary. A string that specifies the part to return.
Start	Necessary. Specifies where to start the string. Positive-starts negative-start 0-starts at the first character in the string
Length	Optional. Specifies the length of the string to return. The default is until the end of the string. Positive number-returns from the position where the start parameter is located Negative-returns from the end of the string

Hints and Notes

Note: If start is negative and length is less than or equal to start, length is 0.

Example

<?php$str = ' Hello world! '; Echo substr ($STR, 4); o world! Start from the 4th to the right to the end of Echo substr ($str, 4, 5); O Wor 5-bit echo substr ($STR, 4,-1) to the right from the left 4th; O World left 4th and right from the 1th character Echo substr ($str,-8, 4); O wo right from the 8th start to intercept the right 4-bit echo substr ($STR, -8,-2); o Worl the 8th and right from the 2nd character?>

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