允许的内存大小为 268435456 字节，数组已用尽

Question

我正在尝试创建一个函数来生成所有可能的组合。这部分效果很好，所以输出将是

aaa aab aac 广告 ...

但现在我正在尝试为每个组合添加扩展名，所以我想在末尾添加“HI”

aaaHI aabHI aacHI aadHI

我尝试了以下但我得到了这个错误。有没有比我正在做的更好的方法来做到这一点？

致命错误：允许的内存大小为 268435456 字节已用尽（尝试分配 100663409 字节）

这是我的脚本

function sampling($chars, $size, $combinations = array()) {

    # if it's the first iteration, the first set 
    # of combinations is the same as the set of characters
    if (empty($combinations)) {
        $combinations = $chars;
    }

    # we're done if we're at size 1
    if ($size == 1) {
        return $combinations;
    }

    # initialise array to put new values in
    $new_combinations = array();

    # loop through existing combinations and character set to create strings
    foreach ($combinations as $combination) {

        foreach ($chars as $char) {
            $new_combinations[] = $combination. $char;
            $new_combinations[] = implode($new_combinations, "HI");
        }
    }

    # call same function again for the next iteration
    return sampling($chars, $size - 1, $new_combinations);

}


// example
$chars = array('a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z');

$output = sampling($chars, 3);

foreach($output as $do) 
{ 
    echo $do."<br>";
} 

Answer 1

这不是很清楚你要做什么，但首先，你错误地使用了implode()。第一个参数必须是 $glue，第二个是你的数组。

string implode ( string $glue , array $pieces )

其次，您的 $new_combinations 数组每一步都在逐步增长。

但如果我明白你要做什么，这段代码对你有用吗：

<?php

function sampling($chars, $size, $combinations = array()) {

    // if it's the first iteration, the first set
    // of combinations is the same as the set of characters
    if (empty($combinations)) {
        $combinations = $chars;
    }

    // we're done if we're at size 1
    if ($size == 1) {
        return $combinations;
    }

    // initialise array to put new values in
    $new_combinations = array();

    // loop through existing combinations and character set to create strings
    foreach ($combinations as $combination) {

        foreach ($chars as $char) {
            $tmp = $combination. $char;
            if ($size == 2) {
                $tmp .= '.com';
            }

            $new_combinations[] = $tmp;
            // I don't get what you were going to do with this line,
            // but this looks like a logical bug in your code
            //$new_combinations[] = implode(".com", $new_combinations);
        }
    }

    // call same function again for the next iteration
    return sampling($chars, $size - 1, $new_combinations);

}


// example
$chars = array('a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z');

$output = sampling($chars, 3);

foreach($output as $do)
{
    echo $do."<br>".PHP_EOL;
}