How To Run And Write First Program In Dev C++

Posted : admin | On 26-04-2021

The best way to learn a programming language is by writing programs. Typically, the first program beginners write is a program called 'Hello World', which simply prints 'Hello World' to your computer screen. Although it is very simple, it contains all the fundamental components C++ programs have:
The left panel above shows the C++ code for this program. The right panel shows the result when the program is executed by a computer. The grey numbers to the left of the panels are line numbers to make discussing programs and researching errors easier. They are not part of the program.
Let's examine this program line by line:
Line 1: // my first program in C++
Two slash signs indicate that the rest of the line is a comment inserted by the programmer but which has no effect on the behavior of the program. Programmers use them to include short explanations or observations concerning the code or program. In this case, it is a brief introductory description of the program.

Line 2: #include <iostream>
Lines beginning with a hash sign (#) are directives read and interpreted by what is known as the preprocessor. They are special lines interpreted before the compilation of the program itself begins. In this case, the directive #include <iostream>, instructs the preprocessor to include a section of standard C++ code, known as header iostream, that allows to perform standard input and output operations, such as writing the output of this program (Hello World) to the screen.

Line 3: A blank line.
Blank lines have no effect on a program. They simply improve readability of the code.

Line 4: int main ()
This line initiates the declaration of a function. Essentially, a function is a group of code statements which are given a name: in this case, this gives the name 'main' to the group of code statements that follow. Functions will be discussed in detail in a later chapter, but essentially, their definition is introduced with a succession of a type (int), a name (main) and a pair of parentheses (()), optionally including parameters.
The function named main is a special function in all C++ programs; it is the function called when the program is run. The execution of all C++ programs begins with the main function, regardless of where the function is actually located within the code.

Lines 5 and 7: { and }
The open brace ({) at line 5 indicates the beginning of main's function definition, and the closing brace (}) at line 7, indicates its end. Everything between these braces is the function's body that defines what happens when main is called. All functions use braces to indicate the beginning and end of their definitions.

Line 6: std::cout << 'Hello World!';
This line is a C++ statement. A statement is an expression that can actually produce some effect. It is the meat of a program, specifying its actual behavior. Statements are executed in the same order that they appear within a function's body.
This statement has three parts: First, std::cout, which identifies the standardcharacter output device (usually, this is the computer screen). Second, the insertion operator (<<), which indicates that what follows is inserted into std::cout. Finally, a sentence within quotes ('Hello world!'), is the content inserted into the standard output.
Notice that the statement ends with a semicolon (;). This character marks the end of the statement, just as the period ends a sentence in English. All C++ statements must end with a semicolon character. One of the most common syntax errors in C++ is forgetting to end a statement with a semicolon.

You may have noticed that not all the lines of this program perform actions when the code is executed. There is a line containing a comment (beginning with //). There is a line with a directive for the preprocessor (beginning with #). There is a line that defines a function (in this case, the main function). And, finally, a line with a statements ending with a semicolon (the insertion into cout), which was within the block delimited by the braces ( { } ) of the main function.
The program has been structured in different lines and properly indented, in order to make it easier to understand for the humans reading it. But C++ does not have strict rules on indentation or on how to split instructions in different lines. For example, instead of

We could have written:
all in a single line, and this would have had exactly the same meaning as the preceding code.
In C++, the separation between statements is specified with an ending semicolon (;), with the separation into different lines not mattering at all for this purpose. Many statements can be written in a single line, or each statement can be in its own line. The division of code in different lines serves only to make it more legible and schematic for the humans that may read it, but has no effect on the actual behavior of the program.
Now, let's add an additional statement to our first program:

In this case, the program performed two insertions into std::cout in two different statements. Once again, the separation in different lines of code simply gives greater readability to the program, since main could have been perfectly valid defined in this way:
The source code could have also been divided into more code lines instead:

And the result would again have been exactly the same as in the previous examples.
Preprocessor directives (those that begin by #) are out of this general rule since they are not statements. They are lines read and processed by the preprocessor before proper compilation begins. Preprocessor directives must be specified in their own line and, because they are not statements, do not have to end with a semicolon (;).

If you are using your own computer, you can save the program wherever you want; however, you should consider creating a folder to hold all of your C.S.1318 programming assignments. If you are using a shared lab machine, you are only able to save your program in the My Documents folder. Working of C 'Hello World!' Program // Your First C Program In C, any line starting with // is a comment. Comments are intended for the person reading. Before you can compile and run your C hello world, you need to install a C compiler. For instance to install the GCC in any Debian based distribution, for instance Ubuntu, do the following: sudo apt-get update; sudo apt-get install build-essential; Create the C Hello World program In Geany you can: create a new file and save it as.c. C Hello World. Now, we will see that how to write C hello world program with Dev C IDE. We can use Dev C for C programming very easily and Dev C makes creating C programs and applications simple for us.


How To Run And Write First Program In Dev C++

Using namespace std

If you have seen C++ code before, you may have seen cout being used instead of std::cout. Both name the same object: the first one uses its unqualified name (cout), while the second qualifies it directly within the namespacestd (as std::cout).
cout is part of the standard library, and all the elements in the standard C++ library are declared within what is called a namespace: the namespace std.
In order to refer to the elements in the std namespace a program shall either qualify each and every use of elements of the library (as we have done by prefixing cout with std::), or introduce visibility of its components. The most typical way to introduce visibility of these components is by means of using declarations:
The above declaration allows all elements in the std namespace to be accessed in an unqualified manner (without the std:: prefix).
With this in mind, the last example can be rewritten to make unqualified uses of cout as:

Both ways of accessing the elements of the std namespace (explicit qualification and using declarations) are valid in C++ and produce the exact same behavior. For simplicity, and to improve readability, the examples in these tutorials will more often use this latter approach with using declarations, although note that explicit qualification is the only way to guarantee that name collisions never happen.
Namespaces are explained in more detail in a later chapter.

C/C for Visual Studio Code (Preview) C/C support for Visual Studio Code is provided by a Microsoft C/C extension to enable cross-platform C and C development on Windows, Linux, and macOS. Getting started C/C compiler and debugger. The C/C extension does not include a. Dev-C by clicking on Help Help on Dev-C. 2 First steps The application development process encompasses the following steps: 1. Create a project The type of application and the programming language to be used are specified. Write source code Write the program in C and save the source code file. Compile and link the code. Jun 08, 2018 Yes, you can. C compilers are able to compile C code. Now, one thing, totally unrelated but please for the love of god stop using Dev-C. Its outdated.

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This walkthrough shows how to create a traditional Windows desktop application in Visual Studio. The example application you'll create uses the Windows API to display 'Hello, Windows desktop!' in a window. You can use the code that you develop in this walkthrough as a pattern to create other Windows desktop applications.

The Windows API (also known as the Win32 API, Windows Desktop API, and Windows Classic API) is a C-language-based framework for creating Windows applications. It has been in existence since the 1980s and has been used to create Windows applications for decades. More advanced and easier-to-program frameworks have been built on top of the Windows API. For example, MFC, ATL, the .NET frameworks. Even the most modern Windows Runtime code for UWP and Store apps written in C++/WinRT uses the Windows API underneath. For more information about the Windows API, see Windows API Index. There are many ways to create Windows applications, but the process above was the first.

Important

For the sake of brevity, some code statements are omitted in the text. The Build the code section at the end of this document shows the complete code.

Prerequisites

  • A computer that runs Microsoft Windows 7 or later versions. We recommend Windows 10 for the best development experience.

  • A copy of Visual Studio. For information on how to download and install Visual Studio, see Install Visual Studio. When you run the installer, make sure that the Desktop development with C++ workload is checked. Don't worry if you didn't install this workload when you installed Visual Studio. You can run the installer again and install it now.

  • An understanding of the basics of using the Visual Studio IDE. If you've used Windows desktop apps before, you can probably keep up. For an introduction, see Visual Studio IDE feature tour.

  • An understanding of enough of the fundamentals of the C++ language to follow along. Don't worry, we don't do anything too complicated.

Create a Windows desktop project

Follow these steps to create your first Windows desktop project. As you go, you'll enter the code for a working Windows desktop application. To see the documentation for your preferred version of Visual Studio, use the Version selector control. It's found at the top of the table of contents on this page.

To create a Windows desktop project in Visual Studio 2019

  1. From the main menu, choose File > New > Project to open the Create a New Project dialog box.

  2. At the top of the dialog, set Language to C++, set Platform to Windows, and set Project type to Desktop.

  3. From the filtered list of project types, choose Windows Desktop Wizard then choose Next. In the next page, enter a name for the project, for example, DesktopApp.

  4. Choose the Create button to create the project.

  5. The Windows Desktop Project dialog now appears. Under Application type, select Desktop application (.exe). Under Additional options, select Empty project. Choose OK to create the project.

  6. In Solution Explorer, right-click the DesktopApp project, choose Add, and then choose New Item.

  7. In the Add New Item dialog box, select C++ File (.cpp). In the Name box, type a name for the file, for example, HelloWindowsDesktop.cpp. Choose Add.

Your project is now created and your source file is opened in the editor. To continue, skip ahead to Create the code.

To create a Windows desktop project in Visual Studio 2017

Language

  1. On the File menu, choose New and then choose Project.

  2. In the New Project dialog box, in the left pane, expand Installed > Visual C++, then select Windows Desktop. In the middle pane, select Windows Desktop Wizard.

    In the Name box, type a name for the project, for example, DesktopApp. Choose OK.

  3. In the Windows Desktop Project dialog, under Application type, select Windows application (.exe). Under Additional options, select Empty project. Make sure Precompiled Header isn't selected. Choose OK to create the project.

  4. In Solution Explorer, right-click the DesktopApp project, choose Add, and then choose New Item.

  5. In the Add New Item dialog box, select C++ File (.cpp). In the Name box, type a name for the file, for example, HelloWindowsDesktop.cpp. Choose Add.

Your project is now created and your source file is opened in the editor. To continue, skip ahead to Create the code.

How To Run And Write First Program In Dev C 2017

To create a Windows desktop project in Visual Studio 2015

Dev

How To Run A Program In Dev C++

  1. On the File menu, choose New and then choose Project.

  2. In the New Project dialog box, in the left pane, expand Installed > Templates > Visual C++, and then select Win32. In the middle pane, select Win32 Project.

    In the Name box, type a name for the project, for example, DesktopApp. Choose OK.

  3. On the Overview page of the Win32 Application Wizard, choose Next.

  4. On the Application Settings page, under Application type, select Windows application. Under Additional options, uncheck Precompiled header, then select Empty project. Choose Finish to create the project.

  5. In Solution Explorer, right-click the DesktopApp project, choose Add, and then choose New Item.

  6. In the Add New Item dialog box, select C++ File (.cpp). In the Name box, type a name for the file, for example, HelloWindowsDesktop.cpp. Choose Add.

Your project is now created and your source file is opened in the editor.

Create the code

Next, you'll learn how to create the code for a Windows desktop application in Visual Studio.

To start a Windows desktop application

  1. Just as every C application and C++ application must have a main function as its starting point, every Windows desktop application must have a WinMain function. WinMain has the following syntax.

    For information about the parameters and return value of this function, see WinMain entry point.

    Note

    What are all those extra words, such as CALLBACK, or HINSTANCE, or _In_? The traditional Windows API uses typedefs and preprocessor macros extensively to abstract away some of the details of types and platform-specific code, such as calling conventions, __declspec declarations, and compiler pragmas. In Visual Studio, you can use the IntelliSense Quick Info feature to see what these typedefs and macros define. Hover your mouse over the word of interest, or select it and press Ctrl+K, Ctrl+I for a small pop-up window that contains the definition. For more information, see Using IntelliSense. Parameters and return types often use SAL Annotations to help you catch programming errors. For more information, see Using SAL Annotations to Reduce C/C++ Code Defects.

  2. Windows desktop programs require <windows.h>. <tchar.h> defines the TCHAR macro, which resolves ultimately to wchar_t if the UNICODE symbol is defined in your project, otherwise it resolves to char. If you always build with UNICODE enabled, you don't need TCHAR and can just use wchar_t directly.

  3. Along with the WinMain function, every Windows desktop application must also have a window-procedure function. This function is typically named WndProc, but you can name it whatever you like. WndProc has the following syntax.

    In this function, you write code to handle messages that the application receives from Windows when events occur. For example, if a user chooses an OK button in your application, Windows will send a message to you and you can write code inside your WndProc function that does whatever work is appropriate. It's called handling an event. You only handle the events that are relevant for your application.

    For more information, see Window Procedures.

To add functionality to the WinMain function

  1. In the WinMain function, you populate a structure of type WNDCLASSEX. The structure contains information about the window: the application icon, the background color of the window, the name to display in the title bar, among other things. Importantly, it contains a function pointer to your window procedure. The following example shows a typical WNDCLASSEX structure.

    For information about the fields of the structure above, see WNDCLASSEX.

  2. Register the WNDCLASSEX with Windows so that it knows about your window and how to send messages to it. Use the RegisterClassEx function and pass the window class structure as an argument. The _T macro is used because we use the TCHAR type.

  3. Now you can create a window. Use the CreateWindow function.

    This function returns an HWND, which is a handle to a window. A handle is somewhat like a pointer that Windows uses to keep track of open windows. For more information, see Windows Data Types.

  4. At this point, the window has been created, but we still need to tell Windows to make it visible. That's what this code does:

    The displayed window doesn't have much content because you haven't yet implemented the WndProc function. In other words, the application isn't yet handling the messages that Windows is now sending to it.

  5. To handle the messages, we first add a message loop to listen for the messages that Windows sends. When the application receives a message, this loop dispatches it to your WndProc function to be handled. The message loop resembles the following code.

    For more information about the structures and functions in the message loop, see MSG, GetMessage, TranslateMessage, and DispatchMessage.

    At this point, the WinMain function should resemble the following code.

To add functionality to the WndProc function

  1. To enable the WndProc function to handle the messages that the application receives, implement a switch statement.

    One important message to handle is the WM_PAINT message. The application receives the WM_PAINT message when part of its displayed window must be updated. The event can occur when a user moves a window in front of your window, then moves it away again. Your application doesn't know when these events occur. Only Windows knows, so it notifies your app with a WM_PAINT message. When the window is first displayed, all of it must be updated.

    To handle a WM_PAINT message, first call BeginPaint, then handle all the logic to lay out the text, buttons, and other controls in the window, and then call EndPaint. For the application, the logic between the beginning call and the ending call is to display the string 'Hello, Windows desktop!' in the window. In the following code, notice that the TextOut function is used to display the string.

    HDC in the code is a handle to a device context, which is a data structure that Windows uses to enable your application to communicate with the graphics subsystem. The BeginPaint and EndPaint functions make your application behave like a good citizen and doesn't use the device context for longer than it needs to. The functions help make the graphics subsystem is available for use by other applications.

  2. An application typically handles many other messages. For example, WM_CREATE when a window is first created, and WM_DESTROY when the window is closed. The following code shows a basic but complete WndProc function.

Build the code

As promised, here's the complete code for the working application.

To build this example

How To Run And Write First Program In Dev C Pdf

  1. Delete any code you've entered in HelloWindowsDesktop.cpp in the editor. Copy this example code and then paste it into HelloWindowsDesktop.cpp:

  2. On the Build menu, choose Build Solution. The results of the compilation should appear in the Output window in Visual Studio.

  3. To run the application, press F5. A window that contains the text 'Hello, Windows desktop!' should appear in the upper-left corner of the display.

Congratulations! You've completed this walkthrough and built a traditional Windows desktop application.

How To Run And Write First Program In Dev C Language

See also