Description of string functions in PHP

This article mainly introduces the description of string functions in PHP, which has certain reference value. Now I share it with everyone. Friends in need can refer to it

PHP String Function

strlen()Get the length

echo strlen("hello world"); output 12

substr(); Returns a part of the string.

echo substr("Hello world",6)."
"; Output world

echo substr("Hello world ",-4)."
"; Output orld

echo substr("Hello world",6,6)."
"; Output world

echo substr("Hello world",0,-6)."
"; Output Hello

substr_count(); Count the number of occurrences of a substring in a string.

;Replace part of the string with another string.

Break the string into an array:

Shift Except whitespace and other characters on both sides of the string.

##echo trim($str,"Hed!");

ltrim()

Remove whitespace characters or other characters on the left side of the string. rtrim()

Remove whitespace characters or other characters on the right side of the string.

str_split()Split the string into an array.

print_r(str_split("Shanghai",3));

Output: Array ( [0] => Sha [1] => ngh [2] => ai )

##str_replace()Replace the string "Hello world!" in "world" replace with "Shanghai": echo str_replace("world","Shanghai","Hello world!");

Reverse the string.

count()The function is used to return the length of the array (number of elements):

strpos()Get the search location

echo strpos("hello world!","world") output 6

Convert the string to

. strtolower() Converts a string to

. strip_tags() Strip HTML and PHP tags from strings

str_word_count() Count the number of words in a string.

strstr()Find the first occurrence of

(for size) of a string in another string write sensitive). stristr()Finds the first occurrence of a string in another string (not case sensitive).

echo strstr("I love Shanghai!","Shanghai"); 函数搜索字符串在另一字符串中的第一次出现。

strtr()转换字符串中特定的字符。

把字符串中的字符 "ia" 替换为 "eo"：

echo strtr("Hilla Warld","ia","eo"); 输出 Hello World

strripos()  查找字符串在另一字符串中最后一次出现的位置

strrpos()   查找字符串在另一字符串中最后一次出现的位置（对大小写敏感）。

strspn();返回在字符串中包含的特定字符的数目。

echo strspn("abcdefand","abc"); 输出 3

is_array() ;判断是否是数字;

存取和修改字符串中的字符

字符串中的字符可以通过一个以0为开始的，用类似数组结构中的方括号包含对应的数字来查找和修改，比如 $str[42] , $str{42}， 可以把 字符串想像数组

$str = 'abcdefghigk';
for($i = 0;$i < strlen($str);$i++){
echo $str[$i].&#39;<br />';或者echo $str{$i}.'<br />';
}die
// 正则校验特殊符号
$word = $f.$h.$o.$n;
if(preg_match("/[\'.,:;*?~`!@ #$%^&+=)(<>{}]|\]|\[|\/|\\\|\"|\|/",$word)){  //不允许特殊字符
}

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