相关疑难解决方法(0)

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This is a collection of questions that come up every now and then about syntax in PHP. This is also a Community Wiki, so everyone is invited to participate in maintaining this list.

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It used to be hard to find questions about operators and other syntax tokens.¹
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我想写一个函数,它将一个字母数组作为参数,并选择一些字母.

假设您提供了8个字母的数组,并希望从中选择3个字母.然后你应该得到:

8! / ((8 - 3)! * 3!) = 56

数组(或单词)返回,每个包含3个字母.

我有一个7个数字(1,2,3,4,5,6,7)的数组,我想要成对的5个数字,如(1,2,3,4,5),(1,2,3) ,4,6,),(1,2,3,4,7).(1,2,3,4,5)等于(4,5,3,1,2)

我想知道PHP或任何算法中是否有函数可以执行此操作？我不知道从哪里开始.你能帮助我吗 ？

我希望将7个给定数字(它们从一个数组中取出)的所有组合放入5个插槽中,无视顺序

我整天都在看PHP数组排列/组合问题..但仍然无法弄明白:/

如果我有一个像这样的数组:

20 //key being 0    
20 //key being 1    
22 //key being 2    
24 //key being 3

我需要组合如:

20, 20, 22 //keys being 0 1 2    
20, 20, 24 //keys being 0 1 3    
20, 22, 24 //keys being 0 2 3
20, 22, 24 //keys being 1 2 3

我目前的代码给了我:

20, 22, 24

因为它不想重复20 ...但这就是我需要的!

这是我的代码.它直接来自Php递归以获得字符串的所有可能性

function getCombinations($base,$n){

$baselen = count($base);
if($baselen == 0){
    return;
}
    if($n == 1){
        $return = array();
        foreach($base as $b){
            $return[] = …