什么是标准调用实际上是宏 [英] What Standard Calls are Actually Macros

问题描述

我在此处询问了有关

I asked a question here about assert which is implemented in the standard as a macro, not a function.

这引起了我一个问题，因为assert似乎是采用参数形式的函数:assert(true)因此，我尝试将其用作:std::assert(true)，当然是一个宏，它没用.

This had caused me an issue because the way that assert appears to be a function in the way it takes a parameter: assert(true) Thus I tried to use it as: std::assert(true) and of course being a macro that didn't work.

我的问题是:标准库是否提供了其他任何带有参数的宏?

My question is this: Are there any other macros provided by the standard library which would appear as functions that take parameters?

推荐答案

如果我们看一下[header]第5和6段，我们就有

If we look at [headers] paragraphs 5 and 6 we have

在C中定义为宏的名称也应在C ++标准库中定义为宏，即使C授予将其实现为功能的许可. [注意:在C中定义为宏的名称包括:assert，offsetof，setjmp，va_arg，va_end和va_start. —尾注]

Names which are defined as macros in C shall be defined as macros in the C++ standard library, even if C grants license for implementation as functions. [ Note: The names defined as macros in C include the following: assert, offsetof, setjmp, va_arg, va_end, and va_start. —end note ]

在C中定义为函数的名称应在C ++标准库中定义为函数.

Names that are defined as functions in C shall be defined as functions in the C++ standard library.

因此，如果在C中将其定义为宏，则它将在C ++中为宏.虽然有一些例外.摘自[support.runtime]第7和8段

So, if it is defined as a macro in C, it will be a macro in C++. There are a couple of exceptions though. from [support.runtime] paragraphs 7 and 8

标头<cstdalign>和标头<stdalign.h>不应定义名为alignas的宏.

The header <cstdalign> and the header <stdalign.h> shall not define a macro named alignas.

标头<cstdbool>和标头<stdbool.h>不应定义名为bool，true或false的宏.

The header <cstdbool> and the header <stdbool.h> shall not define macros named bool, true, or false.

尽管这些例外也包含在[headers]/7中

Although that those exceptions are covered by [headers]/7 as well

在C ++中作为关键字或运算符的标识符不应在C ++标准库标头中定义为宏.

Identifiers that are keywords or operators in C++ shall not be defined as macros in C++ standard library headers.

还有一个例外，即每[c.math]/10

There is also an exception that all classification macros defined in 7.12.3 Classification macros be overloaded by functions per [c.math]/10

分类/比较功能的行为与C宏相同，其相应名称在C标准中的7.12.3(分类宏)和7.12.14(比较宏)中定义.三种浮点类型的每个函数都将重载，如下所示:

The classification/comparison functions behave the same as the C macros with the corresponding names defined in 7.12.3, Classification macros, and 7.12.14, Comparison macros in the C Standard. Each function is overloaded for the three floating-point types, as follows:

int fpclassify(float x);
bool isfinite(float x);
bool isinf(float x);
bool isnan(float x);
bool isnormal(float x);
bool signbit(float x);
bool isgreater(float x, float y);
bool isgreaterequal(float x, float y);
bool isless(float x, float y);
bool islessequal(float x, float y);
bool islessgreater(float x, float y);
bool isunordered(float x, float y);
int fpclassify(double x);
bool isfinite(double x);
bool isinf(double x);
bool isnan(double x);
bool isnormal(double x);
bool signbit(double x);
bool isgreater(double x, double y);
bool isgreaterequal(double x, double y);
bool isless(double x, double y);
bool islessequal(double x, double y);
bool islessgreater(double x, double y);
bool isunordered(double x, double y);
int fpclassify(long double x);
bool isfinite(long double x);
bool isinf(long double x);
bool isnan(long double x);
bool isnormal(long double x);
bool signbit(long double x);
bool isgreater(long double x, long double y);
bool isgreaterequal(long double x, long double y);
bool isless(long double x, long double y);
bool islessequal(long double x, long double y);
bool islessgreater(long double x, long double y);
bool isunordered(long double x, long double y);

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