1. Define (that is, host variable)The main role of the host variable is to act as an alternative variable, a medium in which the host environment can interact with Oracle . When you define a host variable by define, you must specify the variable
#define宏定义在C系开发中可以说占有举足轻重的作用. The underlying framework does not have to say, in order to compile optimization and convenience, as well as cross-platform capabilities, macros are heavily used, it can be said that the bottom of development left define
The Define () function defines a constant.define () functions: Defines a constant. Constants is much like variables, except for the following differences: constants [constant] and variables [variable] There are many similarities, so it is easy to
Thanks to http://blog.chinaunix.net/u3/111961/showart_2187819.html first
. This is an excellent article.
In the last study, we wrote a small client example, which is very simple and the header file generated by using producer-binding-tool is very
Let's look at a few examples
(1) struct{int x; int y;} Test1;
Well, define the structure test1,
test1.x and test1.y can be used in the statement.
(2) struct test {int x; int y;} Test1;
Well, define the structure test1,
test1.x and test1.y can be
# Define is a macro definition Command provided in C language. Its main purpose is to provide programmers with some convenience in programming and improve the program running efficiency to a certain extent, however, students often
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The version number may be used in many places in a VC project, such as the about dialog box and version resource. Changing these values one by one for each version is not only troublesome, but
In # define, the standard defines only # and # #两种操作. #用来把参数转换成字符串, # #则用来连接两个前后两个参数, turn them into a string.#define CONN (x, y) x# #y//connection X, Y#define TOCHAR (x) #@x//Plus Single quote#define TOSTRING (x) #x//plus double quotation
#define是C语言中提供的宏定义命令, the main purpose is to provide programmers with a certain degree of convenience in programming, and to a certain extent to improve the efficiency of the program, but students often do not understand the nature of the command,
For a long time, macro definition # define is used to define some simple constants. At most, it is used to define a function. It seldom pays attention to macro definition usage. Until the following code is displayed:
#define PLAYSOUNDEFFECT(...) \[[
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