问题铸件NAN彩车为int [英] Problems casting NAN floats to int
问题描述
忽略我为什么会想这样做，754 IEEE FP标准没有定义下列行为：
Ignoring why I would want to do this, the 754 IEEE fp standard doesn't define the behavior for the following:
float h = NAN;
printf("%x %d\n", (int)h, (int)h);
Gives: 80000000 -2147483648
基本上，无论我给什么NAN值时，输出8000（十六进制）或-2147483648（DEC）。是否有一个原因和/或这是正确的行为？如果是这样，怎么来的？
Basically, regardless of what value of NAN I give, it outputs 80000000 (hex) or -2147483648 (dec). Is there a reason for this and/or is this correct behavior? If so, how come?
我给它NaN的值不同的方式在这里：
<一href=\"http://stackoverflow.com/questions/10365328/how-can-i-manually-set-the-bit-value-of-a-float-that-equates-to-nan\">How我可以手动设置等同于楠浮动的位值？
The way I'm giving it different values of NaN are here: How can I manually set the bit value of a float that equates to NaN?
因此，基本上，是那里的楠有效载荷影响铸件的产量情况？
So basically, are there cases where the payload of the NaN affects the output of the cast?
谢谢！
推荐答案
一个浮点数强制转换为整数的结果是不确定的值不在整数变量（±1截断）的范围。
The result of a cast of a floating point number to an integer is undefined for values not in the range of the integer variable (±1 for truncation).
A NaN的超出范围，所以结果是不确定的。
A NaN is out of range, so the result is undefined.
事实上，该标准只提到转换的有限的浮点类型为整数类型的值。
In fact, the standard only mentions the conversion of finite values of floating point types to integer types.
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