排序数组-数字，特殊字符，字母 [英] Sort array - digits, special chars, letters

问题描述

我有一组数字，特殊字符和字母.我该如何分类，首先是行家，然后是特殊的字符和字母.

i have array of digits, special chars and letters. How i can sort it that first walked digist, then special chars and leters.

$c64 = str_split(
'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
);

我试图这样做

array_multisort($l64, SORT_DESC);

但是它返回特殊的字符，数字和字母

But it return special chars, digits and letters

推荐答案

这种事情可以以非常聪明"的方式实现，所以我无法抗拒:

This sort of thing can be implemented in very "clever" ways, so I couldn't resist:

$c64 = str_split(
'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
);

$sortValue = function($char) {
    return !ctype_digit($char) << 9 | !ctype_punct($char) << 8 | ord($char);
}

$sortFunction = function($x, $y) use ($sortValue) {
    return $sortValue($x) - $sortValue($y);
};

usort($c64, $sortFunction);

查看实际效果 .

See it in action.

工作方式

我利用了ord返回字符的序数这一事实，这既是普通sort用于对输入进行排序的东西，又是限制在范围[ 0，255]-即它的值使用的位不超过8位.

I 'm taking advantage of the fact that ord returns the ordinal value of a character, which is both what plain sort uses to sort the input and also constrained to the range [0, 255] -- i.e. it uses no more than 8 bits for its value.

此代码正在执行的操作是获取返回值ord(请记住:这是默认sort的工作方式)，并用两个额外的信息对其进行扩充:MSB表示此字符是 not吗? 一个数字?"而LSB表示此字符不是 标点符号吗?".

What this code is doing is taking the return value of ord (remember: that's how the default sort works) and augmenting it with two extra bits of information: the MSB represents "is this character not a digit?" and the LSB represents "is this character not punctuation?".

这些位与序数值进行或运算，产生10位的数量，如下所示:

These bits are ORed together with the ordinal value, producing 10-bit quantities that look like this:

Bit#    10  9  8  7  6  5  4  3  2  1  0
         ^  ^  ^                       ^
         |  |  \-----------+-----------/   
         |  |              \------------- ord
         |  \---------------------------- "not punctuation" bit
         \------------------------------- "not digit" bit

将这些值视为整数时会发生什么?显然，与非数字相对应的值将比其他任何值大，并且与非标点相对应的值也将比字母等大.

What happens when you treat these values as integers? Clearly values that correspond to non-digits are going to be larger than any others, and similarly values that correspond to non-punctuation are going to be larger than letters and such.

因此，通过使用$x - $y的结果确定哪个项目更大，我们实际上是在使数字被认为比其他所有内容都小，标点符号大于数字，但小于非数字.这使得sort在进行升序排序时，将数字放在第一位，然后是标点符号，然后再放入其他所有内容.

So by using the result of $x - $y to determine which item is larger we are in effect making digits be considered smaller than everything else and punctuation larger than digits but smaller than non-digits. This makes sort put digits first, then punctuation, then everything else when it makes an ascending sort.

最后，ord的值参与比较非常重要:对于同一类(例如数字)中的元素，我们希望它们的排序顺序与普通sort的顺序相同生产.

Finally, it is very significant that the value of ord takes part in the comparison: for elements in the same class (e.g. digits) we want their sort order to be the same as the order a plain sort would produce.

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