检查一种整数类型的值是否适合另一种类型 [英] Checking that a value of one integer type fits into another

问题描述

有两种类型 Type1 和 Type2 由不同的标头提供，它们都是某些整数类型的 typedef，但不知道哪个(并且可能不同编译器、操作系统等).这个程序是否保证正常工作(如果它编译)

There are two types Type1 and Type2 provided by different headers, which are both typedefs for some integer types but it isn't known which (and may be different across compilers, OSes, etc. anyway). Is this program guaranteed to work correctly (if it compiles)

Type1 a = ...;
if (a == (Type2) a) {
  printf("a fits into Type2");
else {
  printf("a doesn't fit into Type2");
}

或者是否有我没有考虑的极端情况?

or are there corner cases I am not taking into account?

推荐答案

如果你只担心条目的size，使用sizeof:

If you're only worried about the size of the entry, use sizeof:

if (sizeof(a) == sizeof(Type2)) {
  printf("a fits into Type2");
else {
  printf("a doesn't fit into Type2");
}

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