How to use substr function in PHP

The substr function is used to return a part of the string specified by the parameter. It returns a part of the string by setting the values ​​​​of start and ength.

What I will share with you today is php The substr function in , which is mainly used to return a part of the string specified by the start and length parameters. Next, I will introduce its usage in detail in the article, which has certain reference value and I hope it will be helpful to everyone.

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It has the following syntax:

substr(string,start,length)

Return value: This function returns the part of the string to be extracted, FALSE when it fails, or an empty string. If the start parameter is negative and length is less than or equal to start, length becomes 0

Note: The substr() function is available in PHP 4, PHP 5, PHP 7. In PHP versions 5.2.2 to 5.2.6, if the start parameter represents a negative truncation or an out-of-bounds position, FALSE is returned. Other versions get the string starting at the start position.

Related functions:

strrchr() function is used to find the last occurrence of a string in another string and return the character from that position to All characters at the end of the string

substr_replace() function is used to replace the substring of the string

preg_match() function is used to perform matching regular expressions

trim() function Used to remove whitespace characters or other predefined characters from both sides of a string.

mb_substr() function is used to obtain part of the string

Parameter introduction

string

Used To specify an input string, it must be one character or longer. This is a required parameter.

start

is used to specify the starting position of the returned string. This is a required parameter. If start is non-negative, the returned string will start at the beginning of the string and count from zero. If start is negative, the returned string will start at the starting character at the end of the string.

If the string is shorter than the starting character, return FALSE.

length

is used to specify the length of the returned string. This is an optional parameter. Its default value is the end of the string. If length is given and is positive, the returned string will contain up to length characters starting from start (depending on the length of the string). If length is given and is negative, that many characters will be omitted from the end of the string (after calculating the starting position if it was negative). Returns FALSE if start represents this truncated position or higher.

Note: If the given length is 0, FALSE or NULL, an empty string is returned. If length is omitted, the substring from start to the end of the string is returned

Example sharing:

<?php
echo substr("Hello world",10)."<br>";
echo substr("Hello world",7)."<br>";
echo substr("Hello world",-1)."<br>";
echo substr("Hello world",-8)."<br>";
echo substr("Hello world",0)."<br>";
?>

Rendering:

Summary: The above is the entire content of this article. I hope it will be helpful for everyone to learn PHP to intercept strings

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