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intval碰到小数为什么会减1

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Jun 13, 2016 am 11:57 AM

100intvalnbsp

intval遇到小数为什么会减1
$a = 2.3;
echo ($a*100);//输出230
echo intval($a*100);//输出229
刚开始用的时候我都凌乱了，不知道这是怎么回事
查了好多资料才找到答案，如下
我们看到的：2.3在机器中实际是这样的：2.299999999...具体为什么我也不知道
所以2.3*100在机器中实际是2.299999..*100=229.99...
然后intval作用于他，省略了小数部分，于是就成了229，而不是230
但是intval(1.0)仍然是1，原因是1.0在机器中也是1.0，而不是0.99999...
这种机制应该只会在小数点后发挥作用吧

求大神从根源解释下这个神奇的问题
------解决方案--------------------
printf('%.16f', 2.3); //2.2999999999999998

你在学习计算机基础知识时，没有看二进制小数的章节吗？

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