为什么人们在C ++中使用__（双下划线）
我在看看一些开源的C ++代码，并注意到在代码中使用的很多double，主要是在变量名的开头。
I was having a look through some open source C++ code and notice a lot of double under scores where used in the code, mainly at the start of variable names.
return __CYGWIN__;
只是想知道是有原因的，还是只是一些人的代码样式？我认为我很难阅读。
Just wondering is there a reason for this, or is it just some people code styles? I would think that I makes it hard to read.
标识符中两个下划线（`__'）的使用是为编译器根据ANSI-C标准内部使用而保留的。
The use of two underscores (`__') in identifiers is reserved for the compiler's internal use according to the ANSI-C standard.
）通常用在库函数的名称中（例如_main和_exit）。为避免冲突，请勿使用下划线开始标识符。
Underscores (`_') are often used in names of library functions (such as "_main" and "_exit"). In order to avoid collisions, do not begin an identifier with an underscore.