What are the methods of querying strings in php

Query method: 1. Use stripos() to query the position where the string first appears; 2. Use strpos() to query the position where the string first appears; 3. Use strripos() to query the last position of the string The position of the last occurrence; 4. Use strrpos() to query the position of the last occurrence of the string.

The operating environment of this tutorial: windows7 system, PHP7.1 version, DELL G3 computer

In PHP, you can use the following 4 functions to find the string.

1. Use the stripos() function

stripos() is used to find the first occurrence of a part of a string in a string (not case-sensitive).

The syntax is as follows:

int stripos ( string $haystack , string $needle [, int $offset = 0 ] )

The parameter description is as follows:

• haystack: Search in this string.

• needle: needle can be a single character or multi-character string. If needle is not a string, it is converted to an integer and treated as a character-order value.

• offset: The optional offset parameter allows you to specify which character in the haystack to start searching from. The returned position numeric value is still relative to the starting position of the haystack.

Returns the position where the needle exists at the beginning of the haystack string (independent of the offset). Also note that the string position starts at 0, not 1. If needle is not found, false will be returned.

The example is as follows:

<?php
$findme = &#39;c&#39;;
$mystring1 = &#39;xyz&#39;;
$mystring2 = &#39;ABC&#39;;
$pos1 = stripos($mystring1, $findme);
$pos2 = stripos($mystring2, $findme);
var_dump($pos1);
var_dump($pos2);
?>

The execution result is:

bool(false) int(2)

2. Use strpos() function

strpos() Use to find the first occurrence of a string.

The syntax is as follows:

mixed strpos ( string $haystack , mixed $needle [, int $offset = 0 ] )

strpos() is different from strrpos() and strripos(). The offset of strpos cannot be a negative number.

The example is as follows:

<?php
$findme = &#39;c&#39;;
$findme1 = &#39;C&#39;;
$mystring = &#39;ABCabc&#39;;
$pos1 = strpos($mystring, $findme);
$pos2 = strpos($mystring, $findme1);
var_dump($pos1);
var_dump($pos2);
?>

The execution result of the above code is:

int(5)int(2)

3. Use strripos() function

strripos () is used to calculate the position of the last occurrence of the specified string in the target string (case-insensitive).

The syntax is as follows:

int strripos ( string $haystack , string $needle [, int $offset = 0 ] )

A negative offset will cause the search to start from the beginning of the string and end at the offset position.

The example is as follows:

<?php
$findme = &#39;c&#39;;
$findme1 = &#39;C&#39;;
$mystring = &#39;ABCabcabcABC&#39;;
$pos1 = strripos($mystring, $findme);
$pos2 = strripos($mystring, $findme1);
var_dump($pos1);
var_dump($pos2);
?>

The execution result of the above code is:

int(11)int(11)

4. Use strrpos() function

strrpos () is used to calculate the position of the last occurrence of the specified string in the target string.

The syntax is as follows:

int strrpos ( string $haystack , string $needle [, int $offset = 0 ] )

If it is a negative offset, it will cause the search to be in the string Ends at the count position starting at the end.

The example is as follows:

<?php
$findme = &#39;c&#39;;
$findme1 = &#39;C&#39;;
$mystring = &#39;ABCabcabcABC&#39;;
$pos1 = strrpos($mystring, $findme);
$pos2 = strrpos($mystring, $findme1);
$pos3 = strrpos($mystring, $findme1,-5);
var_dump($pos1);
var_dump($pos2);
var_dump($pos3);
?>

The execution result of the above code is:

int(8)int(11)int(2)

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