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

2/5/2014 How to install CodeBlocks and Get Started with C/C++ Programming

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TABLE OF CONTENTS (HIDE)

1. How to Install CodeBlocks 13.12

2. 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 Errors

4. Debugging C/C++ Program in CodeBlocks

5. Tips and Tweaks

yet another insignificant programming notes... | HOME

CodeBlocks forC/C++Programming

How To Install andGet Started

CodeBlocks is an open-source, cross-platform (Windows, Linux, MacOS), and free C/C++ IDE. It

supports many compilers, such as GNU GCC (MinGW and Cygwin) and MS Visual C++. It supports

interactive debugging (via GNU GDB or MS CDB). CodeBlocks is surprisingly versatile, and in my

opinion, much better than the Visual Studio suite. The mother site of CodeBlocks is

www.codeblocks.org.

1. How to Install CodeBlocks 13.12

Step 1: Download

Goto http://www.codeblocks.org/downloads. Click "Download the binary release". Select your

operating 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 and

GNU 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" ⇒ Select tab

"Toolchain Executables" ⇒ Check the "Compiler's Installation Directory". It shall be set to the

http://www3.ntu.edu.sg/home/ehchua/programming/index.html

http://www.codeblocks.org/

http://www.codeblocks.org/downloads



"MinGW" sub-directory of the CodeBlocks installation directory, for example, suppose that

CodeBlocks is installed in "c:\Program Files\codeblocks", set it to "c:\Program

Files\codeblocks\MinGW".

Similarly, check the debugger's path. Goto "Settings" menu ⇒ "Debugger..." ⇒ Expand "GDB/CDB

debugger" ⇒ Select "Default" ⇒ In "Executable path", provide the full-path name of "gdb.exe", for

example, "c:\Program Files\codeblocks\MinGW\bin\gdb.exe".

Notes For CodeBlocks 13.12 For Windows

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 to

install MinGW"), and configured the compiler's and debugger's path to the installed MinGW

as in the above step.

Alternatively, consider using Eclipse or Netbeans with Cygwin or MinGW GNU GCC

compiler.

2. Writing C/C++ Programs in CodeBlocks

Read:

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://www3.ntu.edu.sg/home/ehchua/programming/howto/Cygwin_HowTo.html#mingw

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



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. A

project contains related files such as source codes, header files, and relevant resources. Also, under

CodeBlocks, you can only debug your program under a project - single-file program (in previous

section) 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 your

working directory, e.g., "d:\project". Accept the default for the rest ⇒ Next.

A project directory "HelloProject" will be created under "d:\project", with a project

configuration filename of "HelloProject.cbp". You could later create more projects

under 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 template

program 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 project

directory 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 the

active 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 all

the source files. That is, you cannot keep two toy programs (each having a main() function) in one

project (you will get the error "multiple definition of 'main'" when you try to build the project). You

need 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 are

not deleted and remain in the folder. We could use this feature to write many toy programs under

one project. The procedures are as follows:

1. Create a C/C++ project called "ToyProgramProject" (read previous section on how to create a

project). You shall get a "main.cpp" automatically.

2. To write another toy program, remove "main.cpp" from the project: right-click on "main.cpp"

⇒ "remove file from project".

3. Add a new file into the project: "File" menu ⇒ "New" ⇒ "File..." ⇒ "C/C++ Source" ⇒ "Go" ⇒

Next ⇒ "C++" ⇒ Next.

a. In "Filename with full path", click the "Navigate" (...) button, enter the filename (e.g.,

Hello.cpp) ⇒ Save.

b. In "Build targets", select "All" (both "Debug" and "Release" ⇒ Finish.

4. Enter your source code.

5. Build and run the program.

6. Check your project directory, which shall show that both the main.cpp and Hello.cpp are

present.

7. Suppose that you wish to run "main.cpp" again: First remove "Hello.cpp" from the project.

Right-click on the project ⇒ Add File... ⇒ Choose "main.cpp" ⇒ Open ⇒ Check both the

"Debug" and "Release" box ⇒ OK. You can now build and run the "main.cpp".

In brief, use the "Add File" and "Remove File" to place your desired toy program file (with the main()

function) under the active project. You can then "Build" the project and "Run" your toy program.

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

that CodeBlocks 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 output

console 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 CodeBlocks

Able to use a graphics debugger to debug program is crucial in programming. It could save you

countless 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 be

used 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?!).

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/*

* 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++;



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}

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 initial

breakpoint at main()

function by clicking on

the "left-margin"

(right-side of the line

number) of the line

containing main(). A red circle appears indicating a breakpoint has been set at that line. A

breakpoint suspends program execution for you to examine the internal states.

Step 2: Start Debugging

From "Debug" menu, select "Start (F8)". The program

begins execution but suspends its execution at the

breakpoint, i.e., main(). An yellow arrow (as shown in

the 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

"Debugging

Windows"

button on

the "Debug"

toolbar and

select

"Watches"

to enable

the "Watch"

pane. (You

could also

do it from

the "Debug"

menu.)



Click the "Next line" button on the

"Debug" toolbar to single-step

thru your program. At each of the

step, 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 program

and watching the values of the variables and the outputs produced is the ultimate mean in

debugging programs - because it is exactly how the computer runs your program!

Step 4: Breakpoint, Run-To-Cursor, Continue and Stop

As mentioned, a breakpoint suspends program execution and let you examine the internal states of

the 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 the

program.

Single-stepping thru a loop with a large count is time-consuming. You could set a breakpoint at the

statement 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" to

resume 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. Explore

the 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 the

first statement of the function. ("Step-Over" runs the function in a single step without stepping

through 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" ⇒ "Edit

Watch..." ⇒ "Add" ⇒ Enter the variable name ⇒ You can select the format, or "watch as array".

5. Tips and Tweaks



1. 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 via menu

"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 list

the available options.

3. Abbreviation: e.g., type "for" and press control-J to get the skeleton of for-loop. The

abbreviation 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 / (zoom

out).

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 & RESOURCES

1. 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 13.12

Last modified: January, 2014

Feedback, comments, corrections, and errata can be sent to Chua Hock-Chuan

([email protected]) | HOME

http://www.codeblocks.org/

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

http://www.codeblocks.org/user-manual

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