c++ - UINT_MIN 的可移植值是多少？

Question

在 limits.h 中，有 INT_MAX 和 INT_MIN(以及 SHRT_* 和 LONG_* 等)的#defines，但是只有 UINT_MAX。

我应该自己定义 UINT_MIN 吗？ 0(正零)是可移植值吗？

Answer 1

它是一个无符号整数 - 根据定义，它的最小可能值为 0。如果你想要一些除了常识之外的理由，standard说:

6.2.6.2 Integer types

1. For unsigned integer types other than unsigned char, the bits of the object representation shall be divided into two groups: value bits and padding bits (there need not be any of the latter). If there are N value bits, each bit shall represent a different power of 2 between 1 and 2^(N−1), so that objects of that type shall be capable of representing values from 0 to 2^(N−1) using a pure binary representation; this shall be known as the value representation. The values of any padding bits are unspecified.