问如何检查SplFixedArray是否包含值？
EN

Stack Overflow用户

提问于 2020-05-16 19:59:15

回答 1查看 133关注 0票数 0

对于普通的数组，我们可以使用in_array()，但in_array不支持SplFixedArray，而且我也找不到任何与splFixedArray in_array()等效的函数，我可以像这样自己执行循环

function spl_in_array(\SplFixedArray &$arr, $value): bool
{
    foreach ($arr as $val) {
        if ($val === $value) {
            return true;
        }
    }
    return false;
}

但这似乎比in_array()慢了大约14-17倍，而且由于SplFixedArray的重点是性能和内存使用(我认为？)...使用此基准测试代码

<?php
declare(strict_types = 1);

$check_iterations = 100;
$nbr_array_values = 100000;
$lookup_value = round($nbr_array_values / 2);

function format(float $f): string
{
    return number_format($f, 6);
}

function spl_in_array(\SplFixedArray &$arr, $value): bool
{
    foreach ($arr as $val) {
        if ($val === $value) {
            return true;
        }
    }
    return false;
}

$arr = [];
for ($i = 0; $i < $nbr_array_values; ++ $i) {
    $arr[] = $i;
}
$splArr = SplFixedArray::fromArray($arr);
$results = [];
$start = microtime(true);
for ($i = 0; $i < $check_iterations; ++ $i) {
    in_array($lookup_value, $arr, true);
}
$end = microtime(true);
$results["in_array"] = $end - $start;
$start = microtime(true);
for ($i = 0; $i < $check_iterations; ++ $i) {
    spl_in_array($splArr, $lookup_value);
}
$end = microtime(true);
$results["spl_in_array"] = ($end - $start);

$results["in_array/spl_in_array"] = $results["in_array"] / $results["spl_in_array"];
$results["spl_in_array/in_array"] = $results["spl_in_array"] / $results["in_array"];
$fastest = ($results["in_array"] > $results["spl_in_array"]) ? "spl_in_array" : "in_array";
foreach ($results as &$result) {
    $result = format($result);
}
$results["fastest"] = $fastest;
print_r($results);

我得到了

Array
(
    [in_array] => 0.001330
    [spl_in_array] => 0.019912
    [in_array/spl_in_array] => 0.066801
    [spl_in_array/in_array] => 14.969887
    [fastest] => in_array
)
Array
(
    [in_array] => 0.001024
    [spl_in_array] => 0.015516
    [in_array/spl_in_array] => 0.065997
    [spl_in_array/in_array] => 15.152270
    [fastest] => in_array
)
Array
(
    [in_array] => 0.001124
    [spl_in_array] => 0.015159
    [in_array/spl_in_array] => 0.074140
    [spl_in_array/in_array] => 13.487908
    [fastest] => in_array
)
Array
(
    [in_array] => 0.000838
    [spl_in_array] => 0.013853
    [in_array/spl_in_array] => 0.060495
    [spl_in_array/in_array] => 16.530299
    [fastest] => in_array
)
Array
(
    [in_array] => 0.000960
    [spl_in_array] => 0.014201
    [in_array/spl_in_array] => 0.067609
    [spl_in_array/in_array] => 14.790911
    [fastest] => in_array
)
Array
(
    [in_array] => 0.000865
    [spl_in_array] => 0.015183
    [in_array/spl_in_array] => 0.056970
    [spl_in_array/in_array] => 17.553197
    [fastest] => in_array
)

因此，使用foreach()手动执行此操作显然不是一种特别有效的方法。

因此出现了这样一个问题:我应该如何检查SplFixedArray是否包含某些内容？in_array()的SplFixedArray等价物是什么？

lookup

spl

php

performance

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回答 1

Stack Overflow用户

发布于 2020-05-16 20:53:21

如果使用->toArray()方法将spl数组转换为标准PHP array，然后使用in_array()，则可以极大地减少时间

$check_iterations = 100;
$nbr_array_values = 100000;
$lookup_value = round($nbr_array_values / 2);

function format(float $f): string
{
    return number_format($f, 6);
}

function spl_in_array(\SplFixedArray &$arr, $value): bool
{
    foreach ($arr as $val) {
        if ($val === $value) {
            return true;
        }
    }
    return false;
}

function new_spl_in_array(\SplFixedArray &$arr, $value): bool
{
    $a = $arr->toArray();
    return in_array($value, $a);
}

$arr = [];
for ($i = 0; $i < $nbr_array_values; ++ $i) {
    $arr[] = $i;
}
$splArr = SplFixedArray::fromArray($arr);
$results = [];
$start = microtime(true);
for ($i = 0; $i < $check_iterations; ++ $i) {
    in_array($lookup_value, $arr, true);
}
$end = microtime(true);
$results["in_array"] = $end - $start;
$start = microtime(true);
for ($i = 0; $i < $check_iterations; ++ $i) {
    spl_in_array($splArr, $lookup_value);
}
$end = microtime(true);
$results["spl_in_array"] = ($end - $start);

$start = microtime(true);
for ($i = 0; $i < $check_iterations; ++ $i) {
    new_spl_in_array($splArr, $lookup_value);
}
$end = microtime(true);
$results["spl_in_array_new"] = ($end - $start);

$results["in_array/spl_in_array"] = $results["in_array"] / $results["spl_in_array"];
$results["spl_in_array/in_array"] = $results["spl_in_array"] / $results["in_array"];
$fastest = ($results["in_array"] > $results["spl_in_array"]) ? "spl_in_array" : "in_array";
foreach ($results as &$result) {
    $result = format($result);
}
$results["fastest"] = $fastest;
print_r($results);

结果

Array
(
    [in_array] => 0.011569
    [spl_in_array] => 1.094222
    [spl_in_array_new] => 0.157041      // < Using ->toArray()
    [in_array/spl_in_array] => 0.010573
    [spl_in_array/in_array] => 94.583991
    [fastest] => in_array
)