C/C ++中的运算符与函数 [英] Operators vs Functions in C/C++

问题描述

最近有人问我C ++标准运算符(例如new，delete，sizeof)和函数(例如tan，free，malloc)之间的区别.标准"是指默认情况下由编译器套件提供的内容，不是用户定义的.下面是我给出的答案，尽管都没有令人满意的答案.

Someone recently asked me the difference between a C++ standard operator (e.g. new,delete,sizeof) and function (e.g. tan,free, malloc). By "standard" I mean those provided by default by the compiler suite, and not user defined. Below were the answers I gave, though neither seemed satisfactory.

(1)运算符不需要使用任何标题即可使用:您可以在不包含任何标题的情况下致电new.但是，一个函数(例如free())确实需要强制包含标头.

(1) An operator doesn't need any headers to be included to use it : E.g. you can have a call to new without including any headers. However, a function (say free() ) does need headers included, compulsorily.

(2)在标准头文件中的某个位置定义了一个运算符(即，一个类运算符).功能不是.

(2) An operator is defined as such (ie as a class operator) somewhere in the standard headers. A function isn't.

您可以批评这些答案，让我对两者之间的区别有更好的了解吗?

Can you critique these answers and give me a better idea of the difference?

推荐答案

运算符是具有固定语法的 关键字 .那些可以重载的语法可能会有所不同，但这是在界限之内的.即使新的 new 运算符仍然拼写为 new ，并且调用它的语法始终相同.

Operators are keywords with a fixed syntax. Those which can be overloaded might vary a bit in syntax, but that's within the boundaries. The new operator is still spelled new, even when overloaded and the syntax of invoking it is always the same.

函数名称是 标识符 ，几乎可以是任意的.没有语法原因，您无法舍弃 malloc()并使用

bool my_fancy_alloc(void*& memory, unsigned char size, bool zero_it);

相反.(马克:还有 其他原因.就像同事的理智一样.)

instead. (Mark: There are other reasons, though. Like your fellow-workers' sanity.)

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