endif

Some programs are debugging, compatibility, in situations like platform porting, you might want to generate a different software by simply setting some parameters, which, of course, can be done with variable settings, write all the possible code,

Reprint: http://blog.chinaunix.net/uid-26854432-id-3181585.html #if语句 #if语句会计算它后面的表达式, and checks the result of the expression, if the result is true (true), the subsequent statement is compiled, and if False (false), the subsequent statement is

#ifndef#define#endif的用法#ifndef#define#endif的用法  你所遇到的这几个宏是为了进行条件编译。一般情况下，源程序中所有的行都参加编译。但是有时希望对其中一部分内容只在满足一定条件才进行编译，也就是对一部分内容指定编译的条件，这就是“条件编译”。有时，希望当满足某条件时对一组语句进行编译，而当条件不满足时则编译另一组语句。     条件编译命令最常见的形式为：     #ifdef 标识符     程序段1     #else     程序段2

What is the effect of this sentence? The condition is always false, used to skip some code snippets, to skip the code between #if 0 and #endif at compile time, which causes #if 0---#endif之间的语句不会被编译, which is a precompiled statement. When commenting

In this paper, we mainly record the pre-C + + preprocessor directives, and the common preprocessing directives are: #空指令, without any effect #include包含一个源代码文件 #define定义宏 #undef取消已定义的宏 #if如果给定条件为真, the following code is

  The pre-processing process scans the source code and performs initial conversion to generate new source code for the compiler. It can be seen that the preprocessing process processes the source code prior to the compiler. In C language, there is

When we look at some open-source code, we often see the following scenarios:# If defined (_ PTHREADS )&&! Defined (_ NOTHREADS)# Define _ STL_PTHREADS# Endif # If defined (_ UITHREADS )&&! Defined (_ PTHREADS )&&! Defined (_ NOTHREADS)# Define _ STL_

Some programs in debugging, compatibility, platform porting and so on may want to create a different software by simply setting some parameters, this can of course, through the variable settings, all the code can be used to write in the

The preprocessing process scans the source code, makes a preliminary conversion, and generates a new source for the compiler. The preprocessing process can be seen before the source code is processed by the compiler.In the C language, there is no

Original address: http://blog.csdn.net/q191201771/article/details/6399820 Here to explain the next few basic knowledge, I believe that most people for the following points are already known, you can also jump to the last part of the

there are always "#ifdef __cplusplus when you look at some programs.extern "C" {#endif"The definition, figuring out what's going on:Microsoft-specific predefined macros__cplusplus Defined forC++programs only. That means, if it's C.++program, you

When you look at some programs, there's always"#ifdef __cplusplusextern "C" {#endif "definition, figuring out what's going on:Microsoft-specific predefined Macros__cplusplus Defined for C + + programs only.This means that if you are a C + + program,

# Ifndef/# define/# endif usage in c/c ++ header files, Presumably many people have read "# ifndef/# define/# endif used in the header file to prevent this header file from being repeatedly referenced ". But can you understand the meaning of "being

Many people have seen " #ifndef/#define/#endif used in the header file to prevent the header file from being repeatedly referenced." But what does it mean to understand "repeated references"? What happens if the header file is repeatedly referenced?

1. In many programs, we will encounter the following code segment # Ifdef _ cplusplusExtern "C "{# Endif // C syntax code segment # Ifdef _ cplusplus}# Endif // First, we should know that __cplusplus is a custom macro in CPP, which indicates that

"# If 0/# if 1... # endif" function, 1. Let's talk about the role of "# if 0/# if 1... # endif" first. You have mentioned a little bit above, but you have not mentioned any key points. We know that the C standard does not provide single-line style

When reading some programs, there are always"# Ifdef _ cplusplusExtern "C "{# Endif "to figure out what is going on: Microsoft-specific predefined macros_ Cplusplus defined for C ++ programs only.It means that if it is a C ++ programExtern "C "{And

it must have been seen by many people. #ifndef/#define/#endif in the header file prevents the header file from being repeatedly referenced. But what does it mean to understand "repeated references"? Is it possible to include this header file in a

Time: 2014.07.01 Location: Base ---------------------------------------------------------------------------- I. Pre-processing details before compiling conditions, first understand the pre-processing process. The pre-processing process reads the

Conditional compilation of pre-processing commands (# ifdef, # else, # endif, # If, etc) Preprocessing is the work done before the first lexical scan and syntax analysis of compilation. To put it bluntly, it is to process the preprocessing part