在php中比较花车 [英] Compare floats in php
问题描述
$ b
$ a = 0.17;我想比较PHP中的两个浮点数,例如:
$ b = 1 - 0.83; /0.17
if($ a == $ b){
echo'a and b are same';
}
else {
echo'a and b are not same';
$ b $ p
$ b 在这段代码中,它返回 else即使 $ a
和 条件而不是 > $ b
是一样的。有没有什么特殊的方法来处理/比较PHP中的浮动?
如果是的话请帮我解决这个问题。
$ b $如果你这样做,他们应该 是一样的。但是请注意,浮点值的一个特点是,导致相同值的计算似乎不需要实际上是相同的。所以如果 $ a
是一个文字 .17
和 $ b
通过一个计算到达那里,它可以是,他们是不同的,虽然都显示相同的值。
通常,你永远不会比较像这样的平等的浮点值,您需要使用最小的可接受差异:
pre $ code if(abs(($ a- $ b)/ $ b)< 0.00001){
echosame;
$ / code>
类似的东西。
I want to compare two floats in PHP, like in this sample code:
$a = 0.17;
$b = 1 - 0.83; //0.17
if($a == $b ){
echo 'a and b are same';
}
else {
echo 'a and b are not same';
}
In this code it returns the result of the else
condition instead of the if
condition, even though $a
and $b
are same. Is there any special way to handle/compare floats in PHP?
If yes then please help me to solve this issue.
Or is there a problem with my server config?
If you do it like this they should be the same. But note that a characteristic of floating-point values is that calculations which seem to result in the same value do not need to actually be identical. So if $a
is a literal .17
and $b
arrives there through a calculation it can well be that they are different, albeit both display the same value.
Usually you never compare floating-point values for equality like this, you need to use a smallest acceptable difference:
if (abs(($a-$b)/$b) < 0.00001) {
echo "same";
}
Something like that.
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