PHP 替换字符串中的一个随机单词 [英] PHP replace a random word of a string

问题描述

我想替换一个字符串中的一个随机单词.

I want to replace one random word of which are several in a string.

所以假设字符串是

$str = 'I like blue, blue is my favorite colour because blue is very nice and blue is pretty';

假设我想用红色替换蓝色这个词，但只在随机位置替换 2 次.

And let's say I want to replace the word blue with red but only 2 times at random positions.

所以在一个函数完成后，输出可能是这样的

So after a function is done the output could be like

I like red, blue is my favorite colour because red is very nice and blue is pretty

另一个可能是

I like blue, red is my favorite colour because blue is very nice and red is pretty

所以我想多次替换同一个词，但每次都在不同的位置.

So I want to replace the same word multiple times but every time on different positions.

我想过使用 preg_match ，但没有选项 peing 替换的单词的位置也是随机的.

I thought of using preg_match but that doesn't have an option that the position of the words peing replaced is random also.

有人知道如何实现这一目标吗?

Does anybody have a clue how to achieve this?

推荐答案

就像我讨厌将正则表达式用于表面上非常简单的事情一样，为了保证完全n 替换 我认为它可以在这里有所帮助，因为它允许使用轻松使用 array_rand()，它完全符合您的要求 - 从不确定长度的列表中选择 n 个随机项目(改进).

Much as I am loathed to use regex for something which is on the face of it very simple, in order to guarantee exactly n replaces I think it can help here, as it allows use to easily use array_rand(), which does exactly what you want - pick n random items from a list of indeterminate length (IMPROVED).

<?php

    function replace_n_occurences ($str, $search, $replace, $n) {

        // Get all occurences of $search and their offsets within the string
        $count = preg_match_all('/\b'.preg_quote($search, '/').'\b/', $str, $matches, PREG_OFFSET_CAPTURE);

        // Get string length information so we can account for replacement strings that are of a different length to the search string
        $searchLen = strlen($search);
        $diff = strlen($replace) - $searchLen;
        $offset = 0;

        // Loop $n random matches and replace them, if $n < 1 || $n > $count, replace all matches
        $toReplace = ($n < 1 || $n > $count) ? array_keys($matches[0]) : (array) array_rand($matches[0], $n);
        foreach ($toReplace as $match) {
            $str = substr($str, 0, $matches[0][$match][1] + $offset).$replace.substr($str, $matches[0][$match][1] + $searchLen + $offset);
            $offset += $diff;
        }

        return $str;

    }

    $str = 'I like blue, blue is my favorite colour because blue is very nice and blue is pretty';

    $search = 'blue';
    $replace = 'red';
    $replaceCount = 2;

    echo replace_n_occurences($str, $search, $replace, $replaceCount);

看看它是否有效

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