在C ++中声明长文字时，是否需要长后缀和无符号后缀? [英] Are long-suffix and unsigned-suffix needed when declaring long literals in C++?

问题描述

我对编写C代码有一些古老的记忆，例如:

I have some ancient memories of writing C code like:

long value = 0;

在糟糕的旧Win16天内

并最终将value初始化为一半:即，低16位是0，高16位是内存中该位置的任意随机位.因此，我变得有条件写:

in the bad old Win16 days and ending up with value being only half-initialized: i.e. the lower 16 bits were 0 and the upper 16 bits were whatever random bits were at that location in memory. As such, I became conditioned to write:

long value = 0L;

在当今的C99和/或C ++时代仍然需要吗?我知道ILP32指定int和long都是32位，但是假设我们使用的是LP64，其中int是32位，而long是64位.后缀是必需的，还是现代形式的C和C ++会将文字直接隐式地扩展到它们被分配给的变量的长度?

Is this still required in this day-and-age under C99 and/or C++? I know that ILP32 specifies that int and long are both 32-bit, but suppose we're using, say, LP64 where ints are 32-bits and longs are 64-bits. Are the suffixes required or will the modern forms of C and C++ implicitly extend literals to the length of the variable they're being assigned to?

无符号值如何? IE.这是必需的吗?

How about unsigned values? I.e. is this required?

unsigned long value = 0UL;

推荐答案

在您提供的示例中，它们不是必需的.但是，在某些默默的情况下可能需要使用它们.例如，以下内容可能会产生不同的值:

They are not required in the examples you gave. However, they may be needed in some somewhat recondite circumstances. For example, the following may produce different values:

sizeof(1)
sizeof(1L)

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