检查浮点数是否为整数 [英] Checking if float is an integer

问题描述

如何检查 float 变量是否包含整数值?到目前为止，我一直在使用:

How can I check if a float variable contains an integer value? So far, I've been using:

float f = 4.5886;
if (f-(int)f == 0)
     printf("yes
");
else printf("no
");

但我想知道是否有更好的解决方案，或者这个解决方案是否有任何(或许多)缺点.

But I wonder if there is a better solution, or if this one has any (or many) drawbacks.

推荐答案

除了已经给出的很好的答案，您还可以使用 ceilf(f) == f 或 floorf(f) == f.如果 f 是整数，则两个表达式都返回 true.他们还为 NaN 返回false (NaN 总是比较 unequal) 和 true 为 ±infinity，并且不会出现溢出用于保存截断结果的整数类型的问题，因为 floorf()/ceilf() return floats.

Apart from the fine answers already given, you can also use ceilf(f) == f or floorf(f) == f. Both expressions return true if f is an integer. They also returnfalse for NaNs (NaNs always compare unequal) and true for ±infinity, and don't have the problem with overflowing the integer type used to hold the truncated result, because floorf()/ceilf() return floats.

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