Introduction to strstr, strpos, substr, strrchr function to find characters in PHP

Introduction to strstr, strpos, substr, strrchr function to find characters in PHP_PHP Tutorial

WBOY

Release： 2016-07-13 17:13:42

Original

1739 people have browsed it

When we search whether a character exists in a string in PHP, we generally use the functions strstr, strpos, substr, strrchr, and stripos, which are commonly used character search functions. Students who need to know more can take a look.

1. strstr — Find the first occurrence of a string

string strstr ( string $haystack , mixed $needle [, bool $before_needle = false ] )
Note 1: $haystack is the subject string, and $needle is the searched string. This function is case-sensitive.
Note 2: The return value is from the beginning to the end of needle.
Note 3: Regarding $needle, if it is not a string, it is treated as an integer and used as the sequence number of the character.
Note 4: If before_needle is true, the previous thing will be returned.

The code is as follows

代码如下	复制代码
$email = 'yuxiaoxiao@example.com'; $domain = strstr($email, '@'); echo $domain; // 打印 @example.com $user = strstr($email, '@', true); // 从 PHP 5.3.0 起 echo $user; // 打印 yuxiaoxiao ?>

Copy code

$email = 'yuxiaoxiao@example.com';

$domain = strstr($email, '@');

echo $domain; // print @example.com
$user = strstr($email, '@', true); // Since PHP 5.3.0
echo $user; // print yuxiaoxiao

2. stristr strstr case-insensitive version

3. strpos - Find the first occurrence of a string

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

Note 1: The optional offset parameter can be used to specify which character in haystack to start searching from. The numerical position returned is relative to the starting position of the haystack.

4. substr - returns the substring of the string

string substr ( string $string , int $start [, int $length ] )

$rest = substr("abcdef", -1); // return "f"

Note 1: If start is a non-negative number, the returned string will start from the start position of string and start counting from 0. For example, in the string "abcdef", the character at position 0 is "a", the character at position 2 is "c", and so on.

Note 2: If start is a negative number, the returned string will start from the start character forward from the end of string.

Note 3: If the length of string is less than or equal to start, FALSE will be returned.

代码如下	复制代码
$rest = substr("abcdef", 0, -1); // 返回 "abcde" $rest = substr("abcdef", 2, -1); // 返回 "cde" $rest = substr("abcdef", 4, -4); // 返回 "" $rest = substr("abcdef", -3, -1); // 返回 "de" ?>

length

Note 4: If a positive length is provided, the returned string will contain at most length characters starting from start (depending on the length of string).

Note 5: If a negative length is provided, many characters at the end of the string will be missed (if start is a negative number, it will be counted from the end of the string). If start is not in this text, an empty string will be returned.

Note 6: If length with a value of 0, FALSE or NULL is provided, an empty string will be returned.

Note 7: If length is not provided, the returned substring will start from the start position until the end of the string.

$rest = substr("abcdef", 2, -1); // return "cde" $rest = substr("abcdef", 4, -4); // return ""

The code is as follows	Copy code
$rest = substr("abcdef", 0, -1); // Return "abcde"

$rest = substr("abcdef", -3, -1); // return "de" <🎜> ?> 5. strrchr - Find the last occurrence of a specified character in a string string strrchr ( string $haystack , mixed $needle ) This function returns a part of the haystack string, starting from the last occurrence of needle and ending at the end of haystack. 6. strripos - calculates the position of the last occurrence of the specified string in the target string (not case sensitive) 7. stripos - Find the position where a string first appears (no distinction between big and small) 8. strrpos - Calculate the position of the last occurrence of the specified string in the target string These functions will only return whether the character you are looking for is stored in the string and return the position or return 0 or 1. If you want to retrieve it from the specified position, we can use substr and other functions to combine operations.