C++ uint8_t、uint16_t、...的格式说明符？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/6993132/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Format specifiers for uint8_t, uint16_t, ...?
提问by Usman
If I have an integer variable I can use sscanfas shown below by using the format specifier %d.
如果我有一个整数变量，我可以sscanf通过使用格式说明符 %d来使用，如下所示。
sscanf (line, "Value of integer: %d\n", &my_integer);
Where can I find format specifiers for uint8_t, uint16_t, uint32_tand uint64_t?
我在哪里可以找到格式说明uint8_t，uint16_t，uint32_t和uint64_t？
uint64_t has probably %lu.
uint64_t 可能有 %lu。
回答by AProgrammer
They are declared in <inttypes.h>as macros: SCNd8, SCNd16, SCNd32 and SCNd64.
Example (for int32_t):
它们被声明<inttypes.h>为宏：SCNd8、SCNd16、SCNd32 和 SCNd64。示例（对于 int32_t）：
sscanf (line, "Value of integer: %" SCNd32 "\n", &my_integer);
Their format is PRI (for printf)/SCN (for scan) then o, u, x, X d, i for the corresponding specifier then nothing, LEAST, FAST, MAX then the size (obviously there is no size for MAX). Some other examples: PRIo8, PRIuMAX, SCNoFAST16.
它们的格式是 PRI（对于 printf）/SCN（对于扫描），然后是 o, u, x, X d, i 对于相应的说明符然后什么都没有，LEAST、FAST、MAX 然后是大小（显然 MAX 没有大小）。其他一些示例：PRIo8、PRIuMAX、SCNoFAST16。
Edit: BTW a related questionasked why that method was used. You may find the answers interesting.
编辑：顺便说一句，一个相关的问题询问了为什么使用该方法。你可能会发现答案很有趣。
回答by Maxim Egorushkin
As others said, include <stdint.h>header that defines the format macros. In C++, however, define __STDC_FORMAT_MACROSprior to including it. From stdint.h:
正如其他人所说，包含<stdint.h>定义格式宏的标头。然而，在 C++ 中，__STDC_FORMAT_MACROS在包含它之前先定义。来自 stdint.h：
/* The ISO C99 standard specifies that these macros must only be
defined if explicitly requested. */
#if !defined __cplusplus || defined __STDC_FORMAT_MACROS
回答by Sebastian Mach
According to 7.19.6 Formatted input/output functionsof ISO/IEC 9899:TC2, there are no such format specifiers (so I doubt there any for C++2003). Even though there are some #define-macros available in C99's inttypes.h, cinttypesand inttypes.hare not part of the current standard. Of course, fixed-size integer types are non-standard as well.
根据ISO/IEC 9899:TC2 的7.19.6 Formatted input/output functions，没有这样的格式说明符（所以我怀疑 C++2003 有没有）。尽管 C99 中有一些 #define-macros 可用，并且不是当前标准的一部分。当然，固定大小的整数类型也是非标准的。inttypes.hcinttypesinttypes.h
Anyways, I seriously recommemend using streams instead:
无论如何，我强烈建议改用流：
<any_type> x;
f >> x;
and be done. E.g.:
并完成。例如：
std::stringstream ss;
uint32_t u;
std::cin >> u;
This has the advantage that one time in the future, changing the type of the variable does not cause a cascade of subtle bugs and undefined behaviour.
这样做的好处是，将来更改变量的类型不会导致一连串微妙的错误和未定义的行为。
回答by Alejandro Caro
The right format to read a uint64_t(typedef unsigned long long int) is, with scanfand not sscanf, "%" SCNu64and for print is also SCNu64Example. in your code you read for example my_integer variable, then you do
scanf ("Value of integer:%" SCNu64, & my_integer);and to write the same but with printf.
读取uint64_t(typedef unsigned long long int)的正确格式是 withscanf和 not sscanf，"%" SCNu64对于打印也是SCNu64示例。在您的代码中，您读取了例如 my_integer 变量，然后您可以
scanf ("Value of integer:%" SCNu64, & my_integer);使用 printf 编写相同的内容。
回答by Jonathan Leffler
In C, the header is <inttypes.h>, and formats such as SCNX8, SCNd16.
在 C 中，标头为<inttypes.h>，以及 SCNX8、SCNd16 等格式。
The same header probably works for C++ too.
相同的头文件可能也适用于 C++。
