多少字节是unsigned long long？ [英] How many bytes is unsigned long long?

问题描述

多少字节是 unsigned long long ？
是否与 unsigned long long int 相同？

推荐答案

执行摘要：它是64位或更大。

Executive summary: it's 64 bits, or larger.

无符号长整型与 unsigned long long int 。它的大小是平台相关的，但由C标准（ISO C99）保证至少为64位。在C89中没有 long long ，但显然甚至MSVC支持它，因此它非常便于移植。

unsigned long long is the same as unsigned long long int. Its size is platform-dependent, but guaranteed by the C standard (ISO C99) to be at least 64 bits. There was no long long in C89, but apparently even MSVC supports it, so it's quite portable.

当前C ++标准（2003年发布），没有 long long ，尽管许多编译器支持它作为扩展。即将到来的C ++ 0x标准将支持它，它的大小将与C中相同，因此至少64位。

In the current C++ standard (issued in 2003), there is no long long, though many compilers support it as an extension. The upcoming C++0x standard will support it and its size will be the same as in C, so at least 64 bits.

您可以获得确切的大小，字节（在典型平台上为8位）与表达式 sizeof（unsigned long long）。如果你只需要64位，使用< stdint.h> 中定义的 uint64_t 一系列相关类型（在C99，C ++ 11和一些当前C ++编译器中可用）。

You can get the exact size, in bytes (8 bits on typical platforms) with the expression sizeof(unsigned long long). If you want exactly 64 bits, use uint64_t, which is defined in the header <stdint.h> along with a bunch of related types (available in C99, C++11 and some current C++ compilers).

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