iab categories

1,Do the site generally encounter the problem of dealing with classification, I have to post several examples of processing infinite classification The structure of the database is simple: ID, fatcher_id, name, ... This design is short and short, fully meet the 3NF. Can be completely overwhelming, OK, let's look at this database structure of the implementation of the program. 1. Recursive query Database The worst way to do it is to do it best. Category 1 Category 1.1 Category 1.1.1 Category 1.2

Storage categories for C + + variables (dynamic storage, static storage, automatic variables, register variables, external variables)dynamic storage mode and static storage mode We've learned about the scope of variables. Scopes are analyzed from the perspective of space, and are divided into global variables and local variables. Variables also have another attribute--the storage period (storage duration, also known as lifetimes). A storage period i

//// Note that there is no annotator in the rgs file. Here "//" is used for instructions. You should remove these comments when using this file.//Hkcr{//// Do not add the noremove before 'component categories 'and 'clsid' Here. If not,// When the component is uninstalled, the two items will be deleted from the Registry. If CLSID is deleted, it will be a tragedy. Prepare to reinstall the system.//Noremove 'component

This article is from E liangshi Yiyou. Today's Mind Map course teaches you how to create layers and categories. Basic sequence ideas in any mind map are the simplest and most obvious sequence generators. They are all key concepts and contain the largest number of associations. The full mind map is differentiated from the small mind map described above only when layers and categories are used. In the smal

Categories (category) in addition to extending the class, the ability to forward references is also strong. For some private methods (no method declared within the. h file) If we want to use it, some use performselector to perform a dynamic call, so that the private method can be called completely, but it is not always a good way to avoid the compiler's syntax checking. Using categories to make forward refe

Categories do not need to introduce a bunch of online (using Objective-c's dynamic runtime allocation mechanism, you can add new methods to existing classes, this way of adding new methods to existing classes is called Category catagory, he can add new methods to any class, including those without source code).This blog mainly wants to discuss questions about categories that cannot add member variables.The

(Type_table_1)Description of name type constraintsType_id int no duplicate category ID, primary keyType_name char (50) cannot be empty or repeatedType_fatherint cannot be null. If it is a top node, it is set to a unique value. This design is short and concise, fully satisfying 3NF, and can satisfy all user requirements. Is that all right? The answer is NO! Why? Let's estimate how the user wants to list the data of this table. For the user, he certainly expects to list all the

Drive Classification:For drivers, we generally classify them in two ways: General taxonomy and bus classification.According to the general classification, can be divided into the following three categories:1. Character Device:ToBytes is the minimum access unitThe device.character device drivers are typically accessed through character device files. The character driver is responsible for driving the character device , which usually supports open, clo

Hello, the C ++ (36) ginseng is good and cannot be used as a meal! How are the 6.3 categories object-oriented?How is class 6.3 object-oriented? Class is a product of the combination of C ++ and object-oriented thinking. as a carrier of Object-oriented Thinking in C ++, it is subject to object-oriented blood. From the composition of Class Members to the inheritance relationship between classes to virtual functions, there are three main features of obje

summarize the storage categories of variables in C + + and the scope of variables .(1) The storage class of the identifier determines the time the identifier exists in memory (we can understand that the identifier is the symbol that determines a variable, that is, the variable name we call)II: Storage category(1) Static storage Category: Static memory category variable (we call static variable), from the beginning of the program exists, its life time

Limitations of the Category(1) A new instance variable cannot be added to the class, and the class has no location to hold the instance variable.(2) name conflict, where the category has a higher precedence when the methods in the category conflict with the original class method name. The class method will completely replace the initial method so that the initial method can no longer be used.Role of the category(1) The implementation of the class is dispersed across several different files or mu

All kinds of errors are encountered during the network data exchange.These network errors are from the client or the server.Let's comb it out:We divide the error into three major categories Operating system error HTTP request Error Application Error 1. The operating system error is due to the failure of the packet to reach the intended target, which may be caused by: No network-no network connection Could not be rout

Understanding the cursor (2) Introduction to the attribute of the cursor and Case Study of Different cursor categories links: Understanding the cursor (1): Overview of the cursor http://www.bkjia.com/database/201212/177395.html PL/SQL provides six types of cursor attributes: The cursor attribute www.2cto.com Name Description Example % FOUND returns true if the record is obtained successfully; otherwise, returns false begin update t set name = 'F' wher

We found that slowly accumulated a lot of their own written in various categories.。 Today, selfless. Posted1.NSDateFomatter@interface NSDateFormatter (mycategory) + (ID) dateformatter;+ (ID) Dateformatterwithformat: (NSString *) dateformat;+ ( ID) defaultdateformatter; @end@implementation NSDateFormatter (mycategory) + (ID) dateformatter{ return [[Self alloc] init];} + (ID) Dateformatterwithformat: (NSString *) dateformat{ NSDateFormatter *datef

the stored data, but SRAM does not need it. DRAM has a long access clock interval, while SRAM is fast and time-consuming. DRAM consumes low power, high power consumption of SRAM. At present, the price of the same capacity of SRAM is about 8 times that of SDRAM, and the area is nearly 4 times larger. Therefore, SRAM is often used for fast storage of low-capacity Ram requirements, such as cache (cache ), for example, the L1 cache in the CPU and the L2 cache on the motherboard are usually only sev

Label: Objective C Category-by using categories, we can dynamically add new methods to existing classes, and modularize the class definitions without being divided into multiple related files. Generally, a method is defined only in a category. 类别，接口部分的定义,通常该文件命名为已有"类+类别名.h"@interface 已有类 （类别名）//.......方法实现@endFor example, if you want to add a category to nsnumber, the interface code is as follows: The implementation of this class is as follows:

Categories allows you to add new methods for a class (you cannot add new data members), instead of using inheritance methods. In addition, you can do this even if there is no implementation source code for a class. Example:I. Example 1:Add several math methods for Fraction without using the fraction source code.1. Code:Put the previously compiled fraction. O and fraction. h in the same directory as the following file. For example, here is the fraction