how to install codeblocks and get started with c_c++ programming

1/9/2015 How to install CodeBlocks and Get Started with C/C++ Programming

http://www.ntu.edu.sg/home/ehchua/programming/howto/CodeBlocks_HowTo.html 1/8

TABLE OF CONTENTS ﴾HIDE﴿

1. How to Install CodeBlocks 13.122. Writing C/C++ Programs in CodeBlocks

2.1 Writing Toy Programs ﴾without Creating a Project﴿2.2 Writing Programs ﴾under Project﴿2.3 Writing Many Toy Programs under ONE Project

3. CodeBlocks' Common Errors4. Debugging C/C++ Program in CodeBlocks5. Tips and Tweaks

yet another insignificant programming notes... | HOME

CodeBlocks forC/C++ProgrammingHow To Install andGet Started

CodeBlocks is an open‐source, cross‐platform ﴾Windows, Linux, MacOS﴿, and free C/C++ IDE. Itsupports many compilers, such as GNU GCC ﴾MinGW and Cygwin﴿ and MS Visual C++. It supportsinteractive debugging ﴾via GNU GDB or MS CDB﴿. CodeBlocks is surprisingly versatile, and in myopinion, much better than the Visual Studio suite. The mother site of CodeBlocks iswww.codeblocks.org.

1. How to Install CodeBlocks 13.12

Step 1: Download

Goto http://www.codeblocks.org/downloads. Click "Download the binary release". Select youroperating platform ﴾e.g., Windows 2000/XP/Vista/7﴿. Download the installer with GCC Compiler, e.g.,codeblocks‐13.12mingw‐setup.exe ﴾98 MB﴿ ﴾which includes MinGW's GNU GCC compiler andGNU GDB debugger﴿.

Step 2: Install

Run the downloaded installer. Accept the default options.

Verify the Compiler's and Debugger's Path : ﴾For CodeBlocks 13.12 For Windows﴿ Goto"Settings" menu ⇒ "Compiler..." ⇒ In "Selected Compiler", choose "GNU GCC Compiler" ⇒ Selecttab "Toolchain Executables" ⇒ Check the "Compiler's Installation Directory". It shall be set to the

http://www.ntu.edu.sg/home/ehchua/programming/index.html

http://www.codeblocks.org/downloads

http://www.codeblocks.org/



"MinGW" sub‐directory of the CodeBlocks installation directory, for example, suppose thatCodeBlocks is installed in "c:\Program Files\codeblocks", set it to "c:\ProgramFiles\codeblocks\MinGW".

Similarly, check the debugger's path. Goto "Settings" menu ⇒ "Debugger..." ⇒ Expand "GDB/CDBdebugger" ⇒ Select "Default" ⇒ In "Executable path", provide the full‐path name of "gdb.exe", forexample, "c:\Program Files\codeblocks\MinGW\bin\gdb.exe".

Notes For CodeBlocks 13.12 For Windows ﴾Jan 2014﴿

I encountered problem running debugger with CodeBlocks 13.12 bundled with MinGW﴾gcc v4.7.1 and gdb 7.5﴿.

I resolved by installing the latast MinGW ﴾gcc 4.8.1, gdb 7.6.1﴿ separately ﴾See "How toinstall MinGW"﴿, and configured the compiler's and debugger's path to the installedMinGW as in the above step.

Alternatively, consider using Eclipse or Netbeans with Cygwin or MinGW GNU GCCcompiler.

2. Writing C/C++ Programs in CodeBlocksRead:

1. CodeBlocks' Wiki @ http://wiki.codeblocks.org/index.php?title=Main_Page, in particular,"Creating a new project" and "Debug my Program".

2.1 Writing Toy Programs ﴾without Creating a Project﴿

To write toy programs ﴾such as few‐line simple programming exercises﴿:

1. File ⇒ New ⇒ Empty File.

2. Enter ﴾copy and paste﴿ the following codes:

// First C++ program to say Hello#include <iostream>using namespace std; int main() { cout << "Hello, world!" << endl; return 0;}

Save the file as "Hello.cpp" in your project directory ﴾e.g., "d:\project"﴿.

3. Build ﴾Compile and Link﴿: Select "Build" menu ⇒ Build ﴾Ctrl‐F9﴿.

4. Run: Select "Build" menu ⇒ Run ﴾Ctrl‐F10﴿.

http://wiki.codeblocks.org/index.php?title=Main_Page

http://www.ntu.edu.sg/home/ehchua/programming/howto/Cygwin_HowTo.html#mingw



The drawback is you cannot debug program without creating a project.

Read "CodeBlocks' Common Errors" if ....

2.2 Writing Programs ﴾under Project﴿

Other than the few‐line toy programs, you shall create a project for each of your application. Aproject contains related files such as source codes, header files, and relevant resources. Also, underCodeBlocks, you can only debug your program under a project ‐ single‐file program ﴾in previoussection﴿ debugging is not supported.

1. File ⇒ New ⇒ Project... ⇒ Console Application ⇒ Go.

2. The "Console Application" wizard appears:

a. Next

b. Select "C++" ⇒ Next.

c. In "Project Title", enter "HelloProject". In "Folder to create project in", set to yourworking directory, e.g., "d:\project". Accept the default for the rest ⇒ Next.A project directory "HelloProject" will be created under "d:\project", with a projectconfiguration filename of "HelloProject.cbp". You could later create more projectsunder this working directory "d:\project".

d. In "Compiler" field, accept the defaults of "GNU GCC Compiler" ⇒ Finish.

3. Under the "Management" pane ⇒ Choose "Projects" tab ⇒ Expand the project node"HelloProject" ⇒ Expand "Source" node ⇒ Double‐click "main.cpp", which is a templateprogram to say "Hello, world!".

4. To build the program, select "Build" menu ⇒ Build.

5. To run the program, select "Build" menu ⇒ Run.

6. To create more source file or header file under the project:

a. File ⇒ New File... ⇒ Select C/C++ source or C/C++ header.

b. C++ ⇒ Next.

c. In "Filename with full path" ⇒ Click the "Navigate" ﴾...﴿ button to navigate to the projectdirectory and enter the new file name. Check both the "Debug" and "Release" boxes ﴾or"All"﴿ ⇒ Finish.

Set Active Project

You can create more projects. However, the "Build" and "Run" commands are always apply to theactive project, which is shown in bold. To activate a project: right‐click on the project name ⇒"Activate Project".

Open an Existing Project

To open an existing project, either:



1. From "File" menu ⇒ "Recent Projects" ⇒ Choose the desired project; or

2. From "File" menu ⇒ "Open..." ⇒ Navigate to your project directory ⇒ Choose"ProjectName.cbp", where ".cbp" stands for CodeBlocks‐Project.

Read "CodeBlocks' Common Errors" if ....

2.3 Writing Many Toy Programs under ONE Project

Although a project may contain many source files, there can only be one main() function among allthe source files. That is, you cannot keep two toy programs ﴾each having a main() function﴿ in oneproject ﴾you will get the error "multiple definition of 'main'" when you try to build the project﴿. Youneed to create one project for each toy program. This is clumsy!

Codeblock, nonetheless, allow you to add files or remove files from a project. The removed files arenot deleted and remain in the folder. We could use this feature to write many toy programs underone project. The procedures are as follows:

1. Create a C/C++ project called "ToyProgramProject" ﴾read previous section on how to create aproject﴿. You shall get a "main.cpp" automatically.

2. Write your toy program on "main.cpp". Build and run the program.

3. To write another program: select "File" ⇒ "Save File as" ⇒ enter a program name such as"myfirst.cpp". Remove it from the project ﴾because each project can only have one file withmain()﴿, by right‐click on "myfirst.cpp" ⇒ "remove file from project".

4. Continue to write your second toy program on "main.cpp". Build and run.

5. Repeat Step 3 and 4 for another toy program.

6. Suppose that you wish to run "myfirst.cpp" again: First remove "main.cpp" from the project.Right‐click on the project ⇒ Add File... ⇒ Choose "myfirst.cpp" ⇒ Open ⇒ Check both the"Debug" and "Release" box ⇒ OK. You can now build and run the "myfirst.cpp".

In brief, use the "Add File" and "Remove File" to place your desired toy program file ﴾with themain() function﴿ under the active project. You can then "Build" the project and "Run" your toyprogram.

3. CodeBlocks' Common Errors

Cannot Compile any C/C++ Program after Installing CodeBlocks

Check:

1. You downloaded the CodeBlocks with "MinGW GNU C/C++ Compiler" ﴾e.g., "codeblocks‐10.05mingw‐setup.exe"﴿.

2. Goto "Settings" menu ⇒ "Compiler..." ⇒ Select tab "Toolchain Executables" ⇒ Check the"Compiler's Installation Directory". It shall be set to the "MinGW" sub‐directory of the



CodeBlocks installation directory, e.g., "c:\Program Files\codeblocks\MinGW" suppose thatCodeBlocks is installed in "c:\Program Files\codeblocks".

Cannot Build or Run Program ‐ Build/Run Buttons and Menu‐Items are Greyand Not Selectable

A previous program is still running. You need to terminate the program by closing the outputconsole window.

Error: undefined reference to `WinMain@16'

Check that you have a main() function in your function. Check your spelling of main!

﴾For C Programs﴿ System Error: "xxx.exe has stopped working"

Check your scanf() function. You probably omitted the '&' before the variable name.

4. Debugging C/C++ Program in CodeBlocksAble to use a graphics debugger to debug program is crucial in programming. It could save youcountless of hours guessing on what went wrong.

Step 0: Write a C++ Program

Follow the steps in "Writing C++ Program ﴾with Project﴿" to write the following C++ program, to beused for the debugging practice. This program computes and prints the factorial of n﴾=1*2*3*...*n﴿. The program, however, has a logical error and produce a wrong answer for n=20.﴾It outputs "The Factorial of 20 is ‐2102132736" ‐ a negative number?!﴿.

12345678910111213141516171819

/* * Compute the factorial of n, with n=20. * n! = 1*2*3*...*n */#include <iostream>using namespace std; int main() { int n = 20; // To compute factorial of n int factorial = 1; // Initialize the product to 1 int i = 1; while (i <= n) { factorial = factorial * i; i++; } cout << "The Factorial of " << n << " is " << factorial << endl; return 0;}



Run the program and observe the output produced:

The Factorial of 20 is ‐2102132736

Let's use the graphic debugger to debug the program.

Step 1: Set an Initial Breakpoint

Set an initialbreakpoint at main()function by clicking onthe "left‐margin"﴾right‐side of the linenumber﴿ of the line

containing main(). A red circle appears indicating a breakpoint has been set at that line. Abreakpoint suspends program execution for you to examine the internal states.

Step 2: Start Debugging

From "Debug" menu, select "Start ﴾F8﴿". The programbegins execution but suspends its execution at thebreakpoint, i.e., main(). An yellow arrow ﴾as shown inthe diagram﴿ appears and points at the main(),indicating this is the next statement to be executed.

Step 3: Single‐Step and Watch the Variables and Outputs

Click the"DebuggingWindows"button onthe"Debug"toolbar andselect"Watches"to enablethe "Watch"pane. ﴾Youcould alsodo it fromthe "Debug" menu.﴿

Click the "Next line" button on the "Debug" toolbar to single‐step thru your program. At each of thestep, you could examine the internal state of your program, such as the value of the variables ﴾in the"Watches" pane﴿, the outputs produced by your program ﴾in the console﴿, etc.



Single‐stepping thru the programand watching the values of thevariables and the outputsproduced is the ultimate mean indebugging programs ‐ because itis exactly how the computer runsyour program!

Step 4: Breakpoint, Run‐To‐Cursor, Continue andStop

As mentioned, a breakpoint suspends program execution and let you examine the internal states ofthe program. To set a breakpoint on a particular line, click the left‐margin of that line ﴾or select"Toggle Breakpoint ﴾F5﴿" from "Debug" menu﴿.

The "Continue" resumes the program execution, up to the next breakpoint, or till the end of theprogram.

Single‐stepping thru a loop with a large count is time‐consuming. You could set a breakpoint at thestatement immediately outside the loop ﴾e.g., Line 12 of the above program﴿, and issue "Continue"to complete the loop.

Alternatively, you can place the cursor on a particular line, right‐click and select "Run‐To‐Cursor" toresume execution up to this line.

The "Stop" ends the debugging session. Always terminate your current debugging session using"Stop" or "Continue" till the end of the program.

Important: I can's stress more that mastering the use of debugger is crucial in programming. Explorethe features provided by the debuggers.

Other Debugging Features

Step‐Into and Step‐Out: To debug a function, you need to use "Step‐Into" to step into thefirst statement of the function. ﴾"Step‐Over" runs the function in a single step without steppingthrough the statements inside the function.﴿ You could use "Step‐Out" to return to the caller,anywhere within the function. Alternatively, you can set a breakpoint inside a function.

Watching a Variable: To add a variable into the "Watches" panel, goto "Debug" ⇒ "EditWatch..." ⇒ "Add" ⇒ Enter the variable name ⇒ You can select the format, or "watch as array".

5. Tips and Tweaks1. Re‐format Source Code: Right‐click on the source file ⇒ Format this file ﴾AStyle﴿.

[Source formatting feature is provided by a plugin called AStyle, which can be accessed viamenu "Plugins" ⇒ "Source Code Formatter ﴾AStyle﴿". To configure the formatting styles, goto



"Settings" ⇒ "Editor..." ⇒ "Source Formatter".]

2. Auto‐Complete: type the initial letters of a keyword/identifier and press Ctrl‐space to listthe available options.

3. Abbreviation: e.g., type "for" and press control‐J to get the skeleton of for‐loop. Theabbreviation list can be configured in "Settings" menu ⇒ "Editor..." ⇒ "Abbreviations".

4. Zoom in/out on Editor Panel: Either:

a. From "Edit" menu ⇒ "Special Commands" ⇒ "Zoom" ⇒ "In", "Out", or "Reset", or

b. Hold the control key and zoom in/out via the mouse scroll wheel, or

c. Use keyboard shortcut: control number‐pad + ﴾zoom in﴿, control number‐pad / ﴾zoomout﴿.

5. Configure Editor: Right‐click on the editor panel ⇒ "Configure editor...".

a. Source Formatter: You can choose the "Java" style.

b. [TODO] more

6. [How to link to API documentation?]

REFERENCES & RESOURCES1. CodeBlocks Mother Site @ http://www.codeblocks.org/.

2. CodeBlocks' Wiki @ http://wiki.codeblocks.org/index.php?title=Main_Page.

3. CodeBlocks' User Manual @ http://www.codeblocks.org/user‐manual.

Latest version tested: CodeBlocks 13.12Last modified: February, 2014

Feedback, comments, corrections, and errata can be sent to Chua HockChuan([email protected]) | HOME

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