The most obvious reason is that if an entity consist of many polygons , the adjacent polygons will share a lot of vertexes , if every polygons has it own vertexes, there will be a lot of redundant data.
The second reason is that dealing with every individual vertex separately are wasteful. Vertex arrays allows you to send vertex data in sets instead of individually.This can improve the performance. OpenGL can process an array of vertexes with just one function call.The second reason is that dealing with every individual vertex separately are wasteful. Vertex arrays allows you to send vertex data in sets .
In SWF, PlaceObject2 called control tag, a list of tags consist of the "Display List". "Display List" is the list of characters that will be displayed in the next frame when play the flash.
PlaceObject2 called control tags, control tags are used to reference object defined by definition tags, like DefineShape,DefineSprite. Definition tags define the object, each object has a unique ID, the CharacterID, these ID stored in dictionary. A control tag get the ID from dictionary and reference the object defined by definition tags.PlaceObject2 called control tags, control tags are used to reference object defined by definition tags, like DefineShape,DefineSprite. Definition tags define the object, each object has .
If you define your member function inside class declaration , they are implicitly inline.
The inline function is supposed to improve the performance by embedding the function body to calling place and so reduce calling cost. It has two disadvantages: add the size of the program and change of the inline function will make caller recompile.
Suppose we have a method DoSomething() will read user input and the input should be a number. If user did not input a number, the method fail to finish its job, so the other code rely on the job should not execute and program should do something about it like show a message to the user, in software programming .
The login information can store in session or cookie. When store in session, the default expire time is when browser is closed.
Change the default by set the session.cookie_lifetime option in php.ini.
In MySQL, you can specify a column as auto_increment, the value will increment 1 at each insert. SQL Server also provide similar thing. Oracle using SEQUENCE and NEXTVAL to do the job.
Create a SEQUENCE:
Oracle provide PL/SQL packages let you extend the database functionality . You can write you own package or utilize the packages shipped with Oracle release.Oracle supplies all kinds of packages, familiar with these packages is a must-have skill of DBA.
Packages is a collection of different program objects include procedures, functions, variables, constants, cursors, exceptions etc.
enum(enumeration) is a user-defined type consisting of a set of enumerators( enumerator --- named integer constant)
Simple enum definition:
When use generate lexer with flex and compile it as cplusplus file, you will get an error like this:
But when compile as c file it will be no problem, if you see the generated c file , you will see: