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    str_split

    (PHP 5, PHP 7, PHP 8)

    str_split — 将字符串转换为数组

    说明

    str_split(string $string, int $length = 1): array

    将一个字符串转换为数组。

    参数

    string

    输入字符串。

    length

    每一段的长度。

    返回值

    如果指定了可选的 length 参数，返回数组中的每个元素长度均为 length 的块，除了最后一个块，如果字符串不是均匀划分，则可能会更短。默认 length 是 1，这意味着每个块的大小是一个字节。

    错误／异常

    如果 length 小于 1，将会抛出 ValueError。

    更新日志

    版本 说明
    8.2.0 如果 string 为空，现在返回空 array。之前返回的 array 包含单个空字符串。
    8.0.0 如果 length 小于 1，现在会抛出 ValueError；之前会触发 E_WARNING 级别的错误且函数会返回 false。

    示例

    示例 #1 str_split() 使用示例

    <?php

    $str     = "Hello Friend";

    $arr1 = str_split($str);
    $arr2 = str_split($str, 3);

    print_r($arr1);
    print_r($arr2);

    ?>

    以上示例会输出：

    Array
(
    [0] => H
    [1] => e
    [2] => l
    [3] => l
    [4] => o
    [5] =>
    [6] => F
    [7] => r
    [8] => i
    [9] => e
    [10] => n
    [11] => d
)

Array
(
    [0] => Hel
    [1] => lo
    [2] => Fri
    [3] => end
)

    注释

    注意:

    在处理多字节字符时，str_split() 会按字节数转换，而非字符数。使用 mb_str_split() 将字符串拆分为码点。

    参见

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    User Contributed Notes 3 notes

    up
    0
    Julian
    1 year ago
    The function str_split() is not 'aware' of words. Here is an adaptation of str_split() that is 'word-aware'.

    <?php

    $array     =  str_split_word_aware(
            'In the beginning God created the heaven and the earth. And the earth was without form, and void; and darkness was upon the face of the deep.',
            32
    );

    var_dump($array);

    /**
      * This function is similar to str_split() but this function keeps words intact; it never splits through a word.
      *
      * @return array<int, string>
      */
    function str_split_word_aware(string $string, int $maxLengthOfLine): array
    {
        if (    $maxLengthOfLine <= 0) {
            throw new     RuntimeException(sprintf('The function %s() must have a max length of line at least greater than one', __FUNCTION__));
        }
       
            $lines = [];
            $words = explode(' ', $string);

            $currentLine = '';
            $lineAccumulator = '';
        foreach (    $words as $currentWord) {

                $currentWordWithSpace = sprintf('%s ', $currentWord);
                $lineAccumulator .= $currentWordWithSpace;
            if (    strlen($lineAccumulator) < $maxLengthOfLine) {
                    $currentLine = $lineAccumulator;
                continue;
            }

                $lines[] = $currentLine;

                // Overwrite the current line and accumulator with the current word
                $currentLine = $currentWordWithSpace;
                $lineAccumulator = $currentWordWithSpace;
        }

        if (    $currentLine !== '') {
                $lines[] = $currentLine;
        }

        return     $lines;
    }

    ?>

    OUTPUT:

    <?php

    array(5) {
      [    0]=> string(29) "In the beginning God created "
          [1]=> string(30) "the heaven and the earth. And "
          [2]=> string(28) "the earth was without form, "
          [3]=> string(27) "and void; and darkness was "
          [4]=> string(27) "upon the face of the deep. "
    }

    ?>
    up
    -7
    lskatz at gmail dot com
    15 years ago
    A good use of str_split is reverse translating an amino acid sequence.

    <?php
    /* reverse translate an aa sequence using its dna counterpart */
    function reverseTranslate($aaSeq,$ntSeq){
          $nt=str_split($ntSeq,3);
          $aa=str_split($aaSeq,1);
          $gapChar=array('*','-');

          $numAa=count($aa);
          $ntIndex=0;
          $newNtSeq="";
      for(    $i=0;$i<$numAa;$i++){
            // if the aa is a gap, then just put on a gap character
            if(in_array($aa[$i],$gapChar)){
              $newNtSeq.='---';
        }
        else{
              $newNtSeq.=$nt[$ntIndex];
              $ntIndex++;
        }
      }
      return     $newNtSeq;
    }
    ?>
    up
    -7
    alex-glebe at mail dot ru
    1 year ago
    Empty string Does'n returns Empty array!

    $arr0 = str_split("");
    print_r($arr0);

    Array
    (
        [0] =>
    )
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