Visual studio

							           Visual Programming

                                   Instructor: Fahad Hassan
                                                 Lecture # 02




1   Fahad Hassan | The University of Lahore
Outline

       Visual Programming
       Advantages & Disadvantages of Visual Programming
       .NET Framework Overview
       Managed VS Un-managed Code
       .NET Framework Components
       Languages and the .NET Framework
       .NET Program Structure
       Types in .NET
       Compilation & Execution of a .NET Application
       Visual C# .NET
       Reading Suggestions
    2                      Fahad Hassan | The University of Lahore
Visual Programming
       A programming language that uses a visual representation
        (such as graphics, drawings, animation or icons, partially or
        completely)
       A visual language manipulates visual information or
        supports visual interaction, or allows programming with
        visual expressions [Golin 90]
       Any system where the user writes a program using two
        or more dimensions [Myers 90]
       A visual language is a set of spatial arrangements of text-
        graphic symbols with a semantic interpretation that is
        used in carrying out communication actions in the world

    3                       Fahad Hassan | The University of Lahore
What are NOT VPLs?



       Visual Basic, Visual C++, Delphi, etc.
           Still primarily textual languages with a graphical GUI builder
           User interface portion of the language is visual, the rest is not




    4                           Fahad Hassan | The University of Lahore
Motivations - Visual Programming

       Many people think in pictures.

       Textual programming languages have proven to be difficult
        for many people to learn to use effectively.

       Some applications are very well suited to graphical
        development approaches.
           Scientific visualization
           System simulation



    5                                  Fahad Hassan | The University of Lahore
Disadvantages of Visual Programming


       As the name implies the entire process of developing an
        application is Visual therefore the development
        environment is highly graphical and requires more
        memory and high speed processor

       Visual development environment can only be used with
        Graphical User Interface operating system like windows



    6                     Fahad Hassan | The University of Lahore
.NET Framework


       The .NET Framework (pronounced dot net) is a software
        framework developed by Microsoft that runs primarily on
        Microsoft Windows. It includes a large library and
        provides language interoperability (each language can use
        code written in other languages) across several
        programming languages.




    7                     Fahad Hassan | The University of Lahore
.NET Framework (Cont…)

       The .NET Framework is a managed, type-safe
        environment for application development and execution.

       The framework manages all aspects of the execution of
        your program: it allocates memory for the storage of data
        and instructions, grants or denies the appropriate
        permissions to your application, initiates and manages
        application execution, and manages the reallocation of
        memory for resources that are no longer needed.


    8                     Fahad Hassan | The University of Lahore
Managed VS Un-managed Code
       Managed code is what Visual Basic .NET and C#
        compilers create. It runs on the CLR (Common Language
        Runtime), which, among other things, offers services like
        garbage collection, run-time type checking, and reference
        checking. So, think of it as, "My code is managed by the
        CLR.“

       Visual Basic and C# can only produce managed code, so, if
        you're writing an application in one of those languages
        you are writing an application managed by the CLR. If you
        are writing an application in Visual C++ .NET you can
        produce managed code if you like, but it's optional.

    9                     Fahad Hassan | The University of Lahore
Managed VS Un-managed Code (Cont…)
    Unmanaged code compiles straight to machine code. So,
     by that definition all code compiled by traditional C/C++
     compilers is 'unmanaged code'. Also, since it compiles to
     machine code and not an intermediate language it is non-
     portable.

    No free memory management or anything else the CLR
     provides.

    Since you cannot create unmanaged code with Visual
     Basic or C#, in Visual Studio all unmanaged code is
     written in C/C++.

    10                 Fahad Hassan | The University of Lahore
.NET Framework Components

    The .NET Framework consists of two main components:
     the common language runtime (CLR) and the .NET
     Framework class library.




    11                Fahad Hassan | The University of Lahore
Common Language Runtime


    The common language runtime can be thought of as the
     environment that manages code execution. It provides
     core services, such as code compilation, memory
     allocation, thread management, and garbage collection.
     Through the common type system (CTS), it enforces
     strict type safety, and it ensures that code is executed in a
     safe environment by enforcing code access security.




    12                   Fahad Hassan | The University of Lahore
.NET Framework class library


    The .NET Framework class library provides a collection
     of useful and reusable types that are designed to integrate
     with the common language runtime.

    The types provided by the .NET Framework are object-
     oriented and fully extensible, and allow you to seamlessly
     integrate your applications with the .NET Framework.



    13                  Fahad Hassan | The University of Lahore
Languages and the .NET Framework

    The .NET Framework is designed for cross-language
     compatibility.

    .NET components can interact with each other no matter
     what language they were originally written in.

    So, an application written in Microsoft Visual Basic .NET
     might reference a DLL file written in Microsoft C#, which
     in turn might access a resource written in managed
     Microsoft C++ or any other .NET language.
    14                 Fahad Hassan | The University of Lahore
.NET Program Execution
    This level of cross-language compatibility is possible
     because of the common language run time.

    When a .NET application is compiled, it is converted from
     the language it was written in (Visual Basic .NET, C#, or
     any other .NET compliant language) to Microsoft
     Intermediate Language (MSIL or IL).

    MSIL/IL is a low-level language designed to be read and
     understood by the common language run time.


    15                 Fahad Hassan | The University of Lahore
.NET Program Execution (Cont…)

    Because all .NET executables and DLLs exist as
     intermediate language, they can freely interoperate.

    The Common Language Specification defines the minimum
     standards that .NET language compilers must conform to,
     and thus ensures that any source code compiled by a
     .NET compiler can interoperate with the .NET
     Framework.



    16                 Fahad Hassan | The University of Lahore
.NET Program Execution (Cont…)

    The CTS ensures type compatibility between .NET
     components. Because .NET applications are converted to
     IL prior to deployment and execution, all primitive data
     types are represented as .NET types. Thus, a Visual Basic
     Integer and a C# int are both represented in IL code as a
     System.Int

    Because both languages use a common and
     interconvertable type system, it is possible to transfer
     data between components and avoid time-consuming
     conversions or hard-to-find errors. 32.

    17                 Fahad Hassan | The University of Lahore
.NET Program Execution (Cont…)




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19   Fahad Hassan | The University of Lahore
.NET Program Structure
    The primary unit of a .NET application is the assembly.

    An assembly is a self-describing collection of code, resources, and
     metadata. The assembly manifest contains information about what is
     contained within the assembly.

    The assembly manifest provides
        Identity information, such as the name and version number of the
         assembly.
        A list of all types exposed by the assembly.
        A list of other assemblies required by the assembly.
        A list of code access security instructions for the assembly. This includes
         a list of permissions required by the assembly and permissions to be
         denied the assembly.


    20                          Fahad Hassan | The University of Lahore
.NET Program Structure (Cont…)

    Each assembly has one and only one assembly manifest,
     and it contains all the description information for the
     assembly.

    The assembly manifest can be contained in its own
     separate file, or it can be contained within one of the
     assembly's modules.




    21                 Fahad Hassan | The University of Lahore
22   Fahad Hassan | The University of Lahore
.NET Program Structure (Cont…)
    An assembly also contains one or more modules.

    A module contains the code that makes up your application or
     library, and metadata that describes that code.

    When you compile a project into an assembly, your code is
     converted from high-level code to IL. Because all managed
     code is first converted to IL code, applications written in
     different languages can easily interact.

    For example, one developer might write an application in
     Visual C# that accesses a DLL in Visual Basic .NET. Both
     resources will be converted to IL modules before being
     executed, thus avoiding any language incompatibility issues.

    23                  Fahad Hassan | The University of Lahore
Types in .NET
    Each module also contains a number of types.

    Types are templates that describe a set of data
     encapsulation and functionality.

    There are two kinds of types: reference types (classes) and
     value types (structures).




    24                  Fahad Hassan | The University of Lahore
Types in .NET (Cont…)
    A type can contain fields, properties, and methods, each
     of which should be related to a common functionality.

    For example, you might have a class that represents a
     bank account. It would contain fields, properties, and
     methods related to the functions needed to implement a
     bank account.




    25                 Fahad Hassan | The University of Lahore
    A field represents storage of a particular type of data. You
     might have a field that stores the name of an account holder.

    Properties are similar to fields, but usually provide some kind
     of validation when the data is set or retrieved. You might have
     a property that represents the balance available in an account.

    When an attempt is made to change the value, the property
     could check to see if the attempted change was greater than a
     predetermined limit, and if so, could disallow the change.



    26                   Fahad Hassan | The University of Lahore
    Methods represent behavior, such as actions taken on
     data stored within the class or changes to the user
     interface.

    Continuing with the bank account example, you might
     have a Transfer method that transfers a balance from a
     checking account to a savings account, or an Alert method
     that warns the user when his balance has fallen below a
     predetermined level.




    27                 Fahad Hassan | The University of Lahore
Compilation & Execution of a .NET App.


    A .NET executable is stored as an IL file. When loaded,
     the assembly is checked against the security policy of the
     local system. If it is allowed to run, the first assembly is
     loaded into memory and JIT compiled into native binary
     code where it is stored for the remainder of the
     program's execution.




    28                  Fahad Hassan | The University of Lahore
Problem Solving Techniques

    How to solve any programmatic problem?

        Decompose the problem
        Make a flow chart for better understanding
        Write Pseudocode
        Translate this code to the actual programming language




    29                      Fahad Hassan | The University of Lahore
Console Application – Tutorial




30            Fahad Hassan | The University of Lahore
Console Application – Tutorial (Cont…)




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32   Fahad Hassan | The University of Lahore
Solution Explorer
    It allows you to navigate around the various files and
     other items that make up your projects and your
     solution.

    Generally, double‐clicking on a file will open that file,
     either in a text editor or perhaps some kind of visual
     design surface. Some files can be edited in various ways.




    33                 Fahad Hassan | The University of Lahore
Error List
    Shows compile time errors, warnings and other related
     messages




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Output
    Displays the output of the program other than the
     console




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How to add/remove any section?




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Console Output




37          Fahad Hassan | The University of Lahore
Visual C# .NET
    Visual C# .NET is part of the Visual Studio family.

    Visual Studio is a complete development environment,
     and it's called the IDE (short for Integrated Development
     Environment). The IDE is the design framework in which
     you build applications; every tool you'll need to create
     your Visual C# .NET projects is accessed from within the
     Visual Studio IDE.

    C# is designed to be a platform-independent language in
     the tradition of Java (although it is implemented primarily
     on Windows).

    38                   Fahad Hassan | The University of Lahore
Visual C# .NET
    It's syntax is similar to C and C++ syntax, and C# is
     designed to be an object-oriented language.

    Another helpful feature of C# is garbage collection.
     Therefore, it is unnecessary to include a destructor for
     each class unless a class handles unmanaged resources; if
     so, it's necessary to release control those resources from
     within the class (The Finalize function is used to clear up
     these unmanaged resources; it can even be abbreviated
     with the same syntax as a C++ destructor). Of course,
     C# also provides direct access to memory through C++
     style pointers, but these pointers are not garbage
     collected until specifically released by the programmer.
    39                  Fahad Hassan | The University of Lahore
Reading Suggestions


    Consult the course site, under Lect 02 folder.
        https://sites.google.com/a/cs.uol.edu.pk/visual-programming/


    Note:  You only need to read page 2 to 8 for
     ProblemSolving.pdf. Rest you need to study all the
     documents.




    40                      Fahad Hassan | The University of Lahore