Hello World in Visual C#

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This topic contains 1 reply, has 2 voices, and was last updated by  LaurenMaskell 11 years, 3 months ago.

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  • #1874


    Here is how Hello World looks in Visual C#:

    Listing 1. Hello World in Visual C# (HelloCS.cs)

    This code is a little longer than the equivalent for Managed Extensions for C++. The syntax for accessing the core library is new; it specifies the namespace rather than the name of the file in which it is found:

    using System;
    The most striking difference is the class specification:

    class MainApp {
    In Visual C#, all code must be contained in methods of a class. So, to house the entry-point code, you must first create a class. (The name of the class does not matter here). Next, you specify the entry point itself:

    public static void Main () {
    The compiler requires this to be called Main. The entry point must also be marked with both public and static. In addition, as with the Managed Extensions for C++ example, the entry point takes no arguments and does not return anything (although different signatures for more sophisticated programs are certainly possible).

    The next line is:

    Console.WriteLine(“Hello World using C#!”);      
    Again, this line writes a string using the runtime Console type. In Visual C#, however, you are able to use a period (.) to indicate the scope. Also, you do not have to place an L before the string because, in C#, all strings are Unicode.

    The Build.bat file contains the single line that is necessary to build this program:

    csc.exe /debug+ /out:.HelloCS.exe helloCS.cs
    In this admittedly simple case, you do not have to specify anything other than the file to compile. In particular, C# does not use the additional step of linking that is required by C++:

    C:…HelloWorldcs>csc.exe /debug+ /out:.HelloCS.exe hellocs.cs
    Microsoft (R) Visual C# Compiler Version …[CLR version…]
    Copyright (C) Microsoft Corp 2000-2001. All rights reserved.
    The default output of the C# compiler is an executable file of the same name, and running this program generates the following output:

    Hello World using Visual C#!

  • #3128

    Can I know what is “HELLO WORLD” for?

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