The difference between #define, const, typedef#define is not defining variables, it's just for text substitution.For example:#define PI 3.1415926float Angel;angel=30*pi/180;Then, when the program is compiled, the compiler will first "#define PI 3.141
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
(PHP 5 >= 5.3.0, PHP 7)
You can also define multiple namespaces in the same file. There are two syntactic forms of defining multiple namespaces in the same file.
Example #1 Define multiple namespaces, simple combination syntax
It is not
Definition:
The # define Directive
You can use the # define directive to give a meaningful name to a constant in your program. The two forms of the syntax are:
Syntax
# Define identifier token-stringopt
# Define identifier [(identifieropt,...,
There are many places in the C language where macro definitions are used, such as in header files to prevent header files from being repeatedly included:
#ifndef ctest_header_h
#define CTEST_HEADER_H
/header file content
#endif
Many macro
Jency LeeLinks: http://www.cnblogs.com/Jency/articles/C_Cplusplus_define.html1. Simple define Definition #define MaxTime + A simple maxtime is defined, which represents 1000 if you write in the program if (i Compiler replaces maxtime with 1000
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
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
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(...) \[[
In the camera flash, define your own "flash" style in the navigation bar. Click on the transformed image to expect it, but it has not changed. The original is the global tint color of the terms. Therefore, the system will actively change the color
The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion;
products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the
content of the page makes you feel confusing, please write us an email, we will handle the problem
within 5 days after receiving your email.
If you find any instances of plagiarism from the community, please send an email to:
info-contact@alibabacloud.com
and provide relevant evidence. A staff member will contact you within 5 working days.