php 如何检查一个整数是否在一个范围内？
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How to check if an integer is within a range?
提问by dynamic
Is there a way to test a range without doing this redundant code:
有没有办法在不执行此冗余代码的情况下测试范围：
if ($int>$min && $int<$max)
?
?
Like a function:
像一个函数：
function testRange($int,$min,$max){
return ($min<$int && $int<$max);
}
usage:
用法：
if (testRange($int,$min,$max))
?
?
Does PHP have such built-in function? Or any other way to do it?
PHP 有这样的内置函数吗？或者有其他方法可以做到吗？
采纳答案by alex
I don't think you'll get a better way than your function.
我不认为你会得到比你的函数更好的方法。
It is clean, easy to follow and understand, and returns the result of the condition (no return (...) ? true : falsemess).
它很干净，易于理解和理解，并返回条件的结果（没有return (...) ? true : false混乱）。
回答by Mark Paspirgilis
Tested your 3 ways with a 1000000-times-loop.
用 1000000 次循环测试了您的 3 种方式。
t1_test1: ($val >= $min && $val <= $max): 0.3823 ms
t1_test1: ($val >= $min && $val <= $max): 0.3823 毫秒
t2_test2: (in_array($val, range($min, $max)): 9.3301 ms
t2_test2: (in_array($val, range($min, $max)): 9.3301 毫秒
t3_test3: (max(min($var, $max), $min) == $val): 0.7272 ms
t3_test3 (max(min($var, $max), $min) == $val)：：0.7272 毫秒
T1 was fastest, it was basicly this:
T1最快，基本上是这样的：
function t1($val, $min, $max) {
return ($val >= $min && $val <= $max);
}
回答by Lars Strojny
There is no builtin function, but you can easily achieve it by calling the functions min()and max()appropriately.
没有内置函数，但您可以通过调用函数min()并max()适当地轻松实现它。
// Limit integer between 1 and 100000
$var = max(min($var, 100000), 1);
回答by Luis Rosety
Most of the given examples assume that for the test range [$a..$b], $a <= $b, i.e. the range extremes are in lower - higher order and most assume that all are integer numbers.
But I needed a function to test if $n was between $a and $b, as described here:
大多数给定的示例假设对于测试范围 [$a..$b]，$a <= $b，即范围极值处于较低 - 较高的顺序，并且大多数假设都是整数。
但是我需要一个函数来测试 $n 是否在 $a 和 $b 之间，如下所述：
Check if $n is between $a and $b even if:
$a < $b
$a > $b
$a = $b
All numbers can be real, not only integer.
There is an easy way to test.
I base the test it in the fact that ($n-$a)and ($n-$b)have different signs when $n is between $a and $b, and the same sign when $n is outside the $a..$b range.
This function is valid for testing increasing, decreasing, positive and negative numbers, not limited to test only integer numbers.
有一种简单的测试方法。
我基地测试的事实，($n-$a)并($n-$b)有不同的符号时，$ n是一个$和$ b之间，与相同的符号，当$ n为$ A .. $ B范围之外。
此函数适用于测试递增、递减、正负数，不限于测试整数。
function between($n, $a, $b)
{
return (($a==$n)&&($b==$n))? true : ($n-$a)*($n-$b)<0;
}
回答by Esa Lindqvist
I'm not able to comment (not enough reputation) so I'll amend Luis Rosety's answer here:
我无法发表评论（没有足够的声誉）所以我会在这里修改 Luis Rosety 的回答：
function between($n, $a, $b) {
return ($n-$a)*($n-$b) <= 0;
}
This function works also in cases where n == a or n == b.
此函数也适用于 n == a 或 n == b 的情况。
Proof: Let n belong to range [a,b], where [a,b] is a subset of real numbers.
证明：设 n 属于范围 [a,b]，其中 [a,b] 是实数的子集。
Now a <= n <= b. Then n-a >= 0 and n-b <= 0. That means that (n-a)*(n-b) <= 0.
现在 a <= n <= b。然后 na >= 0 和 nb <= 0。这意味着 (na)*(nb) <= 0。
Case b <= n <= a works similarly.
情况 b <= n <= a 的工作原理类似。
回答by Krzysiu
There's filter_var()as well and it's the native function which checks range. It doesn't give exactly what you want (never returns true), but with "cheat" we can change it.
还有filter_var()，它是检查 range的本机函数。它并没有给出你想要的（永远不会返回真），但是我们可以通过“作弊”来改变它。
I don't think it's a good code as for readability, but I show it's as a possibility:
我认为就可读性而言，这不是一个好的代码，但我表明这是一种可能性：
return (filter_var($someNumber, FILTER_VALIDATE_INT, ['options' => ['min_range' => $min, 'max_range' => $max]]) !== false)
Just fill $someNumber, $minand $max. filter_varwith that filter returns either boolean false when number is outside range or the number itself when it's within range. The expression (!== false) makes function return true, when number is within range.
只需填写$someNumber,$min和$max。filter_var当数字超出范围时，该过滤器返回布尔值 false 或在范围内时返回数字本身。!== false当数字在范围内时，表达式 ( ) 使函数返回 true。
If you want to shorten it somehow, remember about type casting. If you would use !=it would be false for number 0 within range -5; +5 (while it should be true). The same would happen if you would use type casting ((bool)).
如果您想以某种方式缩短它，请记住类型转换。如果您将使用!=它，则对于 -5 范围内的数字 0 将是错误的；+5（虽然它应该是真的）。如果您使用类型转换 ( (bool))，也会发生同样的情况。
// EXAMPLE OF WRONG USE, GIVES WRONG RESULTS WITH "0"
(bool)filter_var($someNumber, FILTER_VALIDATE_INT, ['options' => ['min_range' => $min, 'max_range' => $max]])
if (filter_var($someNumber, FILTER_VALIDATE_INT, ['options' => ['min_range' => $min, 'max_range' => $max]])) ...
Imagine that (from other answer):
想象一下（来自其他答案）：
if(in_array($userScore, range(-5, 5))) echo 'your score is correct'; else echo 'incorrect, enter again';
If user would write empty value ($userScore = '') it would be correct, as in_arrayis set here for default, non-strict more and that means that range creates 0as well, and '' == 0(non-strict), but '' !== 0(if you would use strict mode). It's easy to miss such things and that's why I wrote a bit about that. I was learned that strict operators are default, and programmer could use non-strict only in special cases. I think it's a good lesson. Most examples here would fail in some cases because non-strict checking.
如果用户将写入空值 ( $userScore = '') 它将是正确的，正如in_array此处设置的默认值，非严格更多，这意味着范围0也会创建，并且'' == 0（非严格），但是'' !== 0（如果您使用严格模式）。很容易错过这样的事情，这就是我写一些关于它的原因。我了解到严格运算符是默认的，程序员只能在特殊情况下使用非严格运算符。我认为这是一个很好的教训。在某些情况下，这里的大多数示例都会因为非严格检查而失败。
Still I like filter_var and you can use above (or below if I'd got so "upped" ;)) functions and make your own callback which you would use as FILTER_CALLBACKfilter. You could return bool or even add openRangeparameter. And other good point: you can use other functions, e.g. checking range of every number of array or POST/GET values. That's really powerful tool.
我仍然喜欢 filter_var 并且你可以使用上面（或下面，如果我得到了如此“提升”;)) 函数并制作你自己的回调，你可以将它用作FILTER_CALLBACK过滤器。您可以返回 bool 甚至添加openRange参数。还有其他好处：您可以使用其他函数，例如检查每个数组或 POST/GET 值的范围。这真是一个强大的工具。
回答by Thom Wiggers
Using comparison operators is way, way faster than calling any function. I'm not 100% sure if this exists, but I think it doesn't.
使用比较运算符比调用任何函数要快得多。我不是 100% 确定这是否存在，但我认为它不存在。
回答by Peter
You could do it using in_array()combined with range()
你可以in_array()结合使用range()
if (in_array($value, range($min, $max))) {
// Value is in range
}
NoteAs has been pointed out in the comments however, this is not exactly a great solution if you are focussed on performance. Generating an array (escpecially with larger ranges) will slow down the execution.
注意正如评论中指出的那样，如果您专注于性能，这并不是一个很好的解决方案。生成数组（尤其是具有更大范围的数组）会减慢执行速度。
