Summary of php string built-in functions

1.strcmp($str1, $str2) If equal, return 0, $str1>$str2 returns 1, $str1<$str2 returns -1 (this is greater than and less than only a comparison of positions, according to the ASCII code table ).

2.strncmp($str1,$str2, $length) intercepts the strings of $str1 and $str2 starting from 0 and has a length of $length for comparison. The output result is the same as the first example.

3.strstr($str, $need, bool $return_before=false) Important string search function This function is equivalent to strchr(), the string operated by $str, the character to be found in $need String, $return_before returns the string with $need before $str. The return value of this function is the first occurrence position of $need string in $str to the last position of $str.

4.strrchr($str, $need) From the last occurrence of $need in string $str to the end of $str

5.$strpos($str,$ need) The position where $need appears for the first time in $str. If the position of $str is not found, null is returned. It is not case sensitive. stripos()

6.strrpos($str,$need)The last time in $str If $need appears, null is returned if not found. If it is not case-sensitive, you can use strripos()

7.strpbrk($str,$charlist) $str is the string to be operated on, $charlist character set ( $charlist = 'abcde'), Search for any character in $charlist in $str, and return the remaining part starting from the first occurrence of the specified character

8.substr($ str,$start,$length) Important String interception function, intercepts the string with a length of $length starting from the $start position in $str

9.explode($delimiter,$ str, $limit=null) string splitting function, $delimiter is the delimiter, $str is the operator, the delimiter cannot be empty, it returns false if it is empty, and returns an array by default.

10.implode($ glue, array $pieces) The important String connection function connects each element of $pieces in the array according to the connector $gule to generate a new string return, which is equivalent to the join() function.

11.str_split($str, $length) splits $str according to the length specified by $length and returns the array. Note that mb_split() is more compatible with Chinese.

12.str_replace($search,$replace,$str) important string replacement function, $search in $str is replaced with $replace.

13.substr_replace ($str,$replacement,$start,$length=null) substring replacement function, the substring of $length starting from $start in $str is replaced with $replacement.

14. str_repeat($str,$times) repeats $str $times times to generate a new string and returns

15.str_pad($str,$pad_length,$pad_str,$pad_type) string filling function, $ The string that str is operated on, $pad_length is the length to be filled, $pad_str is the string used for filling, $pad_type:STR_PAD_LEFT, etc. indicates the position of the filling string.

16.ord(string $char) Return the code value corresponding to ASCII chr (int $ascii) Returns the string corresponding to the ASCII code value

17.strrev($str) String reversal

18.strip_tags($str,$remain_tags), delete html or xml tags as long as <> will be filtered out, you can set the tags that need to be retained in $remain_tags

19.nl2br($str) in the new Add
line break

before the line. Supplement: mb (multibyte) Chinese or other text characters are composed of multiple bytes. Previous string splitting and other functions that did not start with mb all started with a Operations are performed in units of bytes, which will bring unexpected operation results for Chinese characters, so mbstring provides a good operation method.

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