This article introduces, PHP in the Static,const and define usage difference, the need for friends to refer to it.In PHP, often use static,const and define, today we come to understand the difference between the next three what?Define: A macro can be used instead of a constant value, and it can be used instead of an expression or even a code snippet. (Macros are
Yesterday interview by the Group of Examiners asked about the const and define similarities and differences, began to be simple, then asked my head is a group of paste. Almost a summary of the information today1. Const and define.Both can be used to define constants, but the const definition defines the type of the constant, so it is more accurate. #define只是简单的文本
Define the nameset:
A nameset is a multidimensional expression (MDX) that returns a group of dimension members ). You can define a nameset and save it as part of a multi-dimensional dataset definition. You can also apply it on the client.ProgramCreate a nameset. You can create a nameset by combining Multidimensional Dataset data, Arithmetic Operators, numbers, and functions. The name set can be used by the
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# define is a macro definition Command provided in C, the main purpose is to provide some convenience for Program programmers in programming, and to improve the program running efficiency to a certain extent, however, when learning this command, students often cannot understand the essence of the command. It always creates some confusions and misuse it during programming, This
you want to know thisArticleMore details about the things mentioned in. These things can be used as a reference.
Okay. Where can I start? First, we will configure the plug-in that contains the view and add org. Eclipse. UI. navigator to the dependency (dependencies. Then, we use the org. Eclipse. UI. Views extension point to define a view part and use the org. Eclipse. UI. Navigator. commonnavigator class as the implementation class of the view par
Basically, you can use Const,enum or inline to replace a pre-order # define. The main reasons are two:#define Aspect_ratio 1.6531. Pre-processing instructions are preprocessed prior to compilation (GCC-E is preprocessed, its output file is compiled as Gcc-s input), so the compiler is not able to see the symbol Aspect_ratio defined by # define, so it does not appe
1. Const is used for class member variable definition, once defined and cannot change its value. Define defines global constants that can be accessed everywhere.2. Define cannot be defined in a class and const can.3. Const cannot define constants in conditional statementsif (...) {Const FOO = ' BAR '; Invalid}Butif (...) {Def
1. Grammar
Statement:
Parameter data = 8 ' D14;
' Define Data 8 ' D14
Use:Data
' Data
2. Scope
Parameter the file that acts on the Declaration, ' define reads from the compiler until the end of the compilation is valid, or the ' undef command invalidates it.
If you want parameter or ' define to work on the entire project, you can write the following declaration i
When defining constants in PHP, you can use both the const and define methods, so what's the difference between them?1.const the definition of a class member variable, once defined, cannot be modified. Define is not available for definition of class member variables and can be used for global constants.2.const can be used in a class, define cannot.3.const You can
Define section:Macros can be used not only to replace constant values, but also to replace expressions or even code segments. (Macros have powerful functions but are prone to errors, so their advantages and disadvantages are quite controversial .)
Macro Syntax:# Define macro name macro value
As a suggestion and a common habit of programmers, macro names often use uppercase letters.
Advantages of macros:1)
Difference between const and # define,
(1) Different compiler Processing MethodsThe define macro is expanded in the preprocessing phase.
Const constants are used in the compilation and running phase.
(2) Different Types and security checks
The define macro has no type and does not check any type. It just expands.
Const constants have specific types. during compil
This article mainly introduces how to use mini-define to implement modular management of front-end code. it is a very good article. we recommend it to partners who need it.
Mini-define
A simple front-end modular framework based on require. If you don't want to spend time learning require. js or look at the long cmd/amd specifications, then this mini-define is yo
Correct use of IOS macros (define) and constants (const)In iOS development, macro definitions are often used, or some data types are modified with const, and often developers do not know how to use them correctly, resulting in the confusion of macros and const decorations in the project.Can you distinguish between the following? Do you know when to use it?#define Hscoder @"Hansha haha"nsstring *hscoder = @
Define section:Macros can be used not only to replace constant values, but also to replace expressions or even code segments. (Macros have powerful functions but are prone to errors, so their advantages and disadvantages are quite controversial .)Macro Syntax:# Define macro name macro valueAs a suggestion and a common habit of programmers, macro names often use uppercase letters.Advantages of macros:1) make
Not only can you define constants in C + + define , but you can also const define constants with the following differences:
A #define MAX 255 defined constant is no type, given an immediate number, the compiler simply links the defined constant value to the name of the defined constant,
Requirejs file Download, select the version you need toRequirejs using instance Step1 to define an HTML fileWe need to define an HTML file named requirehtml.html.Under File content"">"Utf-8"> "Viewport"Content="Width=device-width, initial-scale=1.0"> introduction of require file,../refers to the parent directory of the directory where the current requirehtml.html file resides. Here is the require.js file un
First, the key:1,Inline functions are the same in readability as functions, while at compile time the functions are embedded directly into the body of the caller, eliminating the call/return instruction, which is faster at run time.
2,Inline functions can be debugged, and macro definitions cannot be debugged.
Inline functions and macros are essentially two different concepts if a program writer has a requirement for both fast and readable conditions, the function should be crowned inline. The
Define section:Macros can be used not only in place of constant values, but also in substitution of expressions or even code snippets. (Macros are powerful, but they are also prone to errors, so the pros and cons are quite controversial.) )
The syntax for macros is:#define Macro Name Macro value
As a suggestion and a common habit of programmers, macro names often use all uppercase letters.
Advantages of
#define Aspect_ratio 1.653The compiler will never see aspect_ratio this symbol name, because before the source code into the compiler, it will be removed by the preprocessor, so aspect_ratio will not be added to the list of symbols. If the code involved in this constant is wrong in compiling the times, it can be confusing because the error message refers to 1.653, not aspect_ratio. If Aspect_ratio is not defined in your own header file, you will wonde
The site needs to add a new constant, open the local config.php file, think about the hidef that was tested a few years ago and the APC upgrade define performance.My program has a different configuration for development, testing, production servers, and in constant terms, we use an array that defines all the constants that need to be defined, and then detects if there is a apc_load_constants function, not a batch
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