How to: Transmit the Message Assigned to an Event Defined in VB.NET
Posted by marius.popa in VB.NET on March 18th, 2010
Appearance of an event and transmission of its message is accomplished by specification RaiseEvent.
Specification RaiseEvent is used only for events declared explicitly.
Use RaiseEvent specification is exemplified in the following source code sequence developed in VB.NET:
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How to: Define Events in Classes Built in VB.NET
Posted by marius.popa in VB.NET on March 18th, 2010
Declaring events in a class built in VB.NET is done using Event specification. Defining event involves assigning the name and arguments providing.
Because an event is included in a class, the objects defined on that class may send messages related to event – raise. Transmission is accomplished by specification RaiseEvent. Assigning the event to procedure for event handling is done by specifications Handles or AddHandler [...].
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How to: Define Delegates in VB.NET
Posted by marius.popa in VB.NET on March 16th, 2010
The delegate is a pointer that allows the call of a function indirectly through its memory address. The delegate is used to call methods of other objects. It is similar to the function pointer used in other programming languages. The difference is that the delegate is a reference type on System.Delegate class.
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How to: Identify Characteristics of Events in VB.NET
Posted by marius.popa in VB.NET on March 16th, 2010
The event is a message sent by an object and announces the application of production a fact.
Events are implemented using delegates [...].
For example, clicking a command button in a graphical interface causes the appearance of the event Click. The event is treated by a procedure.
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How to: Define a Class in VB.NET
Posted by marius.popa in VB.NET on March 9th, 2010
Class is an abstract representation of an entity. The object is a concrete manifestation of a class. The object is the structure that contains data and methods of handling data. An object contains data through fields and properties:
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How to: Use Data Types to Define Variables in VB.NET
Posted by marius.popa in VB.NET on March 9th, 2010
Data types associated to the variables establish the content of data and size of areas used to store data. In VB.NET, the following data types are available for software developer:
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How to: Transform a Mathematical Expression from Infix Writing to Postfix Writing in C++
Posted by marius.popa in C++, Data Structures on February 28th, 2010
Postfix writing (Reverse Polish Form) was made by Polish mathematician Jan Ćukasiewicz. Particularities of this form of writing mathematical expressions are presented in [...].
An algorithm for transforming a writing mathematical expressions from infix to postfix writing was developed by Edsger Dijkstra (Dijkstra Shunting Algorithm).
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How to: Evaluate a Mathematical Expression in Postfix Writing in C++
Posted by marius.popa in C++, Data Structures on February 28th, 2010
Postfix writing [...] is a form of representation of mathematical expressions in which arithmetic operatorsare written specified by operands.
Advantages of postfix writing over prefix and infix writing:
- Highlights clear policy of making operations;
- Brackets for forcing priority for implementing operators are not necessary;
- Evaluations are easily performed by computer.
Librarie de functii si proceduri pentru lucru cu matrici (masive bidimensionale) in limbajul C si C++ – Citire si Afisare
Posted by catalin.boja in Data Structures, Programming on February 6th, 2010
Pentru realizarea calculului matriceal este necesara existenta matricei sau matricelor. Crearea necorespunzatoare a obiectului de lucru, si anume matricea, duce la efecte total neasteptate. De aceea, pentru a fi lipsiti de neplaceri, atentia acordata acestor functii este maxima.
In calculul matriceal sunt incluse si functii de intrare si iesire. Aceste functii realizeaza:
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crearea matricei, fie de la consola ca in cazul bibliotecii matrice.h, fie initializata cu zero ca in cazul clasei matrix( constructorul cu parametrii);
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afisarea matricei pe ecran.
Cum in biblioteca de functii matrice.h se lucreaza cu o matrice de dimensiuni constante, iar in clasa matrix se utilizeaza o variabila de tip pointer, deci dinamic, sunt prezentate ambele moduri de creare( dinamic si static).
In continuare se prezinta functiile care realizeaza creare matricei. In practica se observa, ca pe langa matricea dorita, sunt folosite o serie de matrice ajutatoare cum ar fi matricea unitate, matricea booleana, matricea cu 1 pe o linie si in rest zero etc.. Functiile de creare a acestor matrice sunt functii de intrare, iar afisarea lor este realizata tot cu functii de iesire.
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C and C++ library of functions and procedures for matrix (bidimensional arrays) processing – Read and Write functions
Posted by catalin.boja in Data Structures, Programming on February 6th, 2010
To realize a real computation of matrices it must exist in the first place the matrix or the matrices. Having created an inadequate object for work with it, the results would be unexpected. Therefore we must pay the necessary attention to those functions that are creating a matrix. In this way we won’t have any future troubles.
Matrix processing contains also a sequence of in and out functions. These functions role is:
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to create a matrix from the console when using the library matrix.h or one with all its elements equal with zero when using the class matrix constructor.
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to list a matrix on the computer’ screen
Because the library matrix.h uses a matrix with constant dimensions, and the class matrix uses a dynamic declared matrix, defined with the help of a pointer, both versions of the creating function are described in this chapter.
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