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The difference between define () and const in php is described in detail. In php, both define () and const () can define constants. So what is the difference between define () and const? many programmers do not understand this, next I will introduce some differences between define
In php, both define () and const () can define constants. So what is the difference between define () and const? many programmers do not understand this, I will introduce you In php, both define () and const () can define constants. So what is the difference between
Label: style blog Io ar use for strong SP Div 1) # define is a pre-processing command. It is a simple replacement during compilation and pre-processing, and does not check the correctness. It does not mean that it is correct or not, possible errors are detected and reported only when the expanded source program is compiled. For example:# Define PI 3.1415926In the program: Area = pI * r will be replaced with
1.1. # define variant, that is, # ifndef, can prevent repeated references to header files# Ifdef and # define combinations are generally used in header files to prevent repeated references of multiple files to the same header file.In actual use, even if your header file is not referenced by multiple files, it is best to add it to increase program readability, portability, robustness, and so on.Its usage is
Today, we have compiled some # define usage to share with you!1. Simple define Definition#define MAXTIME 1000A simple maxtime is defined, it represents 1000, if it is written inside the programif (IThe compiler replaces the maxtime with 1000 before processing the code.Such a definition looks similar to a normal const definition, but it is also different because t
dbus_glib _ $ (prefix) _ object_info. The header file wei_server.h is generated as follows: /* Generated by using-binding-tool; do not edit! */ # Ifndef _ dbus_glib_marshal_com_wei_MARSHAL_H __ # Define _ dbus_glib_marshal_com_wei_MARSHAL_H __ # Include G_BEGIN_DECLS # Ifdef G_ENABLE_DEBUG # Define g_marshal_value_peek_boolean (v) g_value_get_boolean (v) #
Define is a pre-processing command in C language. It is used for macro definition, which can improve the readability of the source code and provide convenience for programming.Pre-processing commands start with "#", for example, include commands # include and macro-defined commands # define. Usually put in front of the source file, which is called preprocessing.Preprocessing refers to the work done before c
A constant is an identifier (first name) of a simple value. As the name implies, the value cannot be changed during script execution (except for the so-called magic constants, they are not constants). Changshime is considered to be case sensitive. Usually, constant identifiers are always uppercase. You can use the Define () function to define constants. After PHP 5.3.0, you can use the Const keyword to
In PHP define () and const () can define constants, then the difference between define () and const exactly where, this many programmers do not understand, I would like to introduce to you some of this function usage ratio. The difference between define () and const: 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 confuse; Let's enumerate the differences between constants [constant] and variables [variable]: A constant's value cannot be changed after it is set a constant value cannot be changed after it has been specif
# Define usage 1.Simple define Definition # Define maxtime1000 A simple maxtime is defined. It represents 1000. If you write If (I The compiler replaces maxtime with 1000 before processing this code. This definition looks similar to a normal constant definition const, but it is also different, because the definition of defin
Const is used for the definition of class member constants. it cannot be modified after definition, and define is used to define global constants, so that we can access but cannot change it elsewhere, we will list the details below. note: define cannot be defined in... const is used for the definition of class member constants. it cannot be modified after definit
Usage and difference between typedef and # define I. Usage of typedef In C/C ++, typedef is often used to define an alias for an identifier and a keyword. It is part of the language compilation process, but it does not actually allocate memory space, such: Typedef int;Typedef int array [10];Typedef (int *) pint; Typedef can be enhancedProgramBut it also has some disadvantages such as "non-intuitive.
Http://blog.sina.com.cn/s/blog_686188ef0100klku.html#define是C语言中提供的宏定义命令, the main purpose is to provide programmers with certain convenience in programming, and to a certain extent, improve the efficiency of the program, but students often do not understand the nature of the command in learning, always create some confusion here, in the programming of the misuse of the command, To make the program run inconsistent with the intended purpose, or to rea
#define是C语言中提供的宏定义命令, the main purpose is to provide programmers with certain convenience in programming, and to a certain extent, improve the efficiency of the program, but students often do not understand the nature of the command in learning, always create some confusion here, in the programming of the misuse of the command, To make the program run inconsistent with the intended purpose, or to read the program written by others, the results of the
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 used in the statement. Compared with 1, the province wrote Test (3) typedef struct TEST {int x; int y; } TEXT1,TEXT2; Only said that the structure of the (
In general, we define a constant using # define, #define的本质是文本替换, for example, # define INT_PTR int*, when we use a int_ptr,int_ptr a, B, which is equivalent to an INT * A, A, a, b; That is, define a pointer variable A and integer variable B, which is a common scenario for #
1 NO parameter macro definitionThe macro name of the parameterless macro is not followed by a parameter.The general form of its definition is:#define Identifier stringWhere the "#" indicates that this is a preprocessing command. All that begin with "#" are pre-processing commands. "Define" defines the command for the macro. "Identifier" is the name of the macro defined. A "string" can be a constant, an expr
Note: Define cannot be defined in a class, and the const must be defined in a class, and the const must be accessed by the class name:: Variable name 1. Const is used for class member variable definition once defined and cannot change its value. Define defines global constants that can be accessed anywhere.2, define can not be defined in the class and Const.3. C
: This article mainly introduces the difference between const and define in php (supplement). If you are interested in PHP tutorials, refer to it. A constant is the identifier (name) of a simple value ). As its name implies, this value cannot be changed during script execution (except for so-called magic constants, they are actually not constants ). Constants are case sensitive by default. Constant identifiers are always capitalized. You can use the
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