mb_substr

• (PHP 4 >= 4.0.6, PHP 5, PHP 7)
• mb_substr — Get part of string
• mb_substr — 獲取部分字串

Description

string mb_substr ( 
    string $str ,
    int $start [,
    int $length = NULL [, 
    string $encoding = mb_internal_encoding() ]] 
    )
// Performs a multi-byte safe substr() operation based on number of characters. Position is counted from 
// the beginning of str. First character`s position is 0. Second character position is 1, and so on.
//根據字元數執行一個多位元組安全的 substr() 操作。 位置是從 str 的開始位置進行計數。 第一個字元的位置是 0。第二個字元的位置是 1，以此類推。

Parameters

str

• The string to extract the substring from.
• 從該 string 中提取子字串。

start

• If start is non-negative, the returned string will start at the start`th position in str, counting from zero. For instance, in the string `abcdef`, the character at position 0 is `a`, the character at position 2 is `c`, and so forth.
• 如果 start 不是負數，返回的字串會從 str 第 start 的位置開始，從 0 開始計數。舉個例子，字串 `abcdef`，位置 0 的字元是 `a`，位置 2 的字元是 `c`，以此類推。
• If start is negative, the returned string will start at the start`th character from the end of str.
• 如果 start 是負數，返回的字串是從 str 末尾處第 start 個字元開始的。

length

• Maximum number of characters to use from str. If omitted or NULL is passed, extract all characters to the end of the string.
• str 中要使用的最大字元數。如果省略了此引數或者傳入了 NULL，則會提取到字串的尾部。

encoding

• The encoding parameter is the character encoding. If it is omitted, the internal character encoding value will be used.
• encoding 引數為字元編碼。如果省略，則使用內部字元編碼。

Return Values

• mb_substr() returns the portion of str specified by the start and length parameters.
• mb_substr() 函式根據 start 和 length 引數返回 str 中指定的部分。

Changelog

• 5.4.8 – Passing NULL as length extracts all characters to the end of the string. Prior to this version NULL was treated the same as 0.

Examples

<?php
/**
 * Created by PhpStorm.
 * User: zhangrongxiang
 * Date: 2018/1/30
 * Time: 下午8:51
 */

$string = "0123456789你好";
/** start > 0  length > 0*/
$mystring = mb_substr( $string, 5, 1 );
echo $mystring . PHP_EOL; // 5
$mystring = mb_substr( $string, 5, 2 );
echo $mystring . PHP_EOL; // 56
$mystring = mb_substr( $string, 10, 2 );
echo $mystring . PHP_EOL; // 你好

/** start < 0  length > 0*/
$mystring = mb_substr( $string, - 2, 2 );
echo $mystring . PHP_EOL; // 你好
echo `mb_strlen : ` . mb_strlen( $string ) . PHP_EOL;//12
$mystring = mb_substr( $string, - mb_strlen( $string ), 2 );
echo $mystring . PHP_EOL; // 01
$mystring = mb_substr( $string, - 3, 2 );
echo $mystring . PHP_EOL; // 9你

/** start > 0  length <  0*/
$mystring = mb_substr( $string, 5, - 1 );
echo $mystring . PHP_EOL; // 56789你
$mystring = mb_substr( $string, 0, - mb_strlen( $string ) + 1 );
echo $mystring . PHP_EOL; // 0
$mystring = mb_substr( $string, 5, - 5 );
echo $mystring . PHP_EOL; // 56

/** start < 0  length <  0*/
$mystring = mb_substr( $string, - 10, - 1 );
echo $mystring . PHP_EOL; // 23456789你
$mystring = mb_substr( $string, - 5, - 1 );
echo $mystring . PHP_EOL; // 789你

function mb_ucfirst( $str, $enc = `utf-8` ) {
    return mb_strtoupper( mb_substr( $str, 0, 1, $enc ), $enc ) . mb_substr( $str, 1, mb_strlen( $str, $enc ), $enc );
}

echo mb_ucfirst( "hello world 你好 中國" ) . PHP_EOL; //Hello world 你好 中國

/**
 * @param $string
 * @param string $encoding
 *
 * @return array
 */
function get_character_classes( $string, $encoding = "UTF-8" ) {
    $current_encoding = mb_internal_encoding();
    mb_internal_encoding( $encoding );
    $has          = array();
    $stringlength = mb_strlen( $string, $encoding );
    for ( $i = 0; $i < $stringlength; $i ++ ) {
        $c = mb_substr( $string, $i, 1 );
        if ( ( $c >= "0" ) && ( $c <= "9" ) ) {
            $has[`numeric`] = "numeric";
        } else if ( ( $c >= "a" ) && ( $c <= "z" ) ) {
            $has[`alpha`]      = "alpha";
            $has[`alphalower`] = `alphalower`;
        } else if ( ( $c >= "A" ) && ( $c <= "Z" ) ) {
            $has[`alpha`]      = "alpha";
            $has[`alphaupper`] = "alphaupper";
        } else if ( ( $c == "$" ) || ( $c == "£" ) ) {
            $has[`currency`] = "currency";
        } else if ( ( $c == "." ) && ( $has[`decimal`] ) ) {
            $has[`decimals`] = "decimals";
        } else if ( $c == "." ) {
            $has[`decimal`] = "decimal";
        } else if ( $c == "," ) {
            $has[`comma`] = "comma";
        } else if ( $c == "-" ) {
            $has[`dash`] = "dash";
        } else if ( $c == " " ) {
            $has[`space`] = "space";
        } else if ( $c == "/" ) {
            $has[`slash`] = "slash";
        } else if ( $c == ":" ) {
            $has[`colon`] = "colon";
        } else if ( ( $c >= " " ) && ( $c <= "~" ) ) {
            $has[`ascii`] = "ascii";
        } else {
            $has[`binary`] = "binary";
        }
    }
    mb_internal_encoding( $current_encoding );
    
    return $has;
}

$string = "1234asdfA£^_{}|}~žščř";
foreach ( get_character_classes( $string ) as $k => $v ) {
    echo $k . " : " . $v . PHP_EOL;
}
//numeric : numeric
//alpha : alpha
//alphalower : alphalower
//alphaupper : alphaupper
//currency : currency
//ascii : ascii
//binary : binary

文章參考

• http://php.net/manual/en/func…

轉載註明出處