The definition of APC constant is compared with define of PHP. Recently, when I was working on the preliminary code architecture of the cloud platform, I encountered a constant definition speed comparison problem, so I would like to make a comparison. Php apc extension, which is described in the following section in the PHP Manual: h recently encountered a constant definition speed comparison problem when working on the preliminary code architecture o
Use hidef extension in PHP instead of define to improve performance, hidefdefine. In PHP, hidef extension is used instead of define to improve performance. hidefdefine requires a new constant to open the local config. PHP file, think of hidef tested a few years ago and apc to improve PHP using hidef extension instead of define to improve performance, hidefdefine
A constant is a simple identifier. This value cannot be changed during script execution (in addition to the so-called magic constants, they are not constants). Constants are case sensitive by default. Usually, constant identifiers are always uppercase.
can be used define () function to define constants. After php5.3.0, you can use the Const keyword to define
Macro definition ' DefineRepresents a string with a specified identifier (that is, the name), which is in its general form:' Define identifier (macro name) string (macro content)such as: ' Define signal stringIts function is to specify the identifier signal instead of string, in the process of compiling preprocessing, all the signal after the command is replaced by string. This method allows the user to rep
ES6 (ECMAScript 6) is the upcoming new version of the JavaScript language standard, code-named Harmony (meaning of harmony, obviously did not keep pace with our country, we have entered the Chinese Dream version). The last standard was enacted in 2009 ES5. The ES6 is currently in the process of standardization and is expected to release the officially finalized version in December 14. But most of the standards are in place, and browser support for ES6 is also being implemented.
The way in which
css|frontpage| Web page
Note: The latest version of FrontPage is Frontpagexp (FrontPage 2003), this article is about Frontpage2000, but the method described in this article is basically applicable in Frontpagexp! Another, This is only discussed in Frontpage2000 how to define CSS, as for the knowledge of CSS, please refer to the relevant information.
When many people find it convenient to define CSS in DW4,
Defining constants is best used with static const, without # defineConstants are often defined when writing code. For example, to write a UI view class, the view is displayed and then the animation is played, and then disappears. You may want to extract the time to play the animation as a constant. People who have mastered Objective-c and their C-language base may do so in this way:#define ANIMATION_DURATION 0.3The preprocessing instructions above rep
The Application of C ++ programming language is flexible. Its appearance has brought a lot of help to programmers. So what are the features of other programming languages? Let's start with the features of the C ++ # define pre-processing command and compare it with other languages.
C ++ # define pre-processing commands define so-called symbolic constants, which a
1. const is used for defining class member variables. Once defined, the value cannot be changed. Define defines global constants that can be accessed anywhere.2. define cannot be defined in the class, But const can.3. const cannot define constants in condition statements.Copy codeThe Code is as follows:If (...){Const FOO = 'bar'; // invalid}ButIf (...){
In C or C + +, you can declare a new type in place of an existing type by using typedef and define. For example:typedef int COUNT;#define COUNT int;Both work by using count to represent an int. Although the two functions are the same, there is actually a big difference, otherwise they will not exist at the same time. The following is a brief discussion of the difference between the two, hoping to use the co
#define N OK#define N 100; Error#define N = + Error int A[n] = int a[=] Error#define PIN int* pin, A, b; Error (A is int*,b int)2. Special usage#define BEGIN {#define END}int main BEGINprintf ("haha");ENDDefine a loop#
Summary:Const is used instead of a fixed value of # define, and inline is used instead of # define a function. is an upgraded version of # define, in order to eliminate the defect of # define.the difference between #define和inlineDefine: defines a macro that is processed during precompilation ;simple character substitut
Macro definitionA macro definition is a definition of some common variables, strings, and so on, and the defined data is automatically replaced in the compilation. Sometimes some variables or strings are used more than once, when the need to modify, you need to the source files where they appear in one by one, the efficiency is low, and through the macro definition, only need to modify the definition, you can achieve batch modification, improve efficiency, or sometimes some numbers or characters
within the STL, the Map,set is implemented using the same red-black tree, the map corresponds to the template parameter key_type,mapped_type, and the set The corresponding template parameter has no mapped_typeboth support insert operationsPair??for Maptypedef pairfor SetTypdef Key_type Value_type;??so in the extension library Pb_ds ( code in ext/pb_ds) It 's designed like this, like trie.Triesays key is string,mapped is intTriesays that key is a string without mapped similar to a trieset conce
Define fact relationships :
You sometimes need to define the dimension of the measurement value based on the data items in the fact data table, or query other specific information in the fact data table, such as the invoice number related to the specific sales situation or the purchase order number. When a dimension is defined based on such fact data table items, the dimension is called a "fact dimension "
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The typedef keyword and # define have a common function. A custom name is created for a type, as shown in figure
Typedef int Myint;
# Define Myint int
They are the same, but they are still quite different.
Typedef statements are parsed during compilation, while # define statements are parsed during
1. Definition Format of one-dimensional array typeTypedef For example:(1) typedef int vector [10];(2) typedef char strings [80];(3) typedef short int array [N];The first statementDefines an array type vector whose element type is int and contains 10 elements. If typedef reserved words are not used, the elements are defined as arrays, it only defines an array vector whose element type is int and contains 10 elements. These two definitions have essential differences. If we
iOS uses macros to define functions and blocks of codeToday, in the development process, there is a problem: it is the parent class to send out notifications, and then in the subclass or other class to receive it. Of course, it is generally written into the class method, but there is a problem, that is, if the calling class is not its subclass, it can not be directly invoked, of course, it is also possible to implement the static method, I am here mai
To define an array type using typedef statements1. Defining formats for one-dimensional array types typedef For example: (1) typedef int VECTOR[10]; (2) typedef char STRINGS[80]; (3) typedef short INT array[n]; The first statement defines an array-type vector with an element type of int, containing 10 elements, and, without a typedef reserved word, becomes an array definition, which defines only an array vector with an element type of int and 10
Use occasion: Splicing two macros, one is the incoming macro. But the incoming macros will not be replaced, but it will be awkward to take them up. After a variety of attempts, incredibly became, hereby record sharing, convenient for everyone to learn.
Char a_param=0;
Char b_pramm=0; Add a macro definition#define OBJECT A#define DEFINE_ (X) x# #_param//Once defined#defi
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