Writing code in linux

How To Compile And Run a C/C++ Code In Linux

I am a new Linux user and student who used to write C or C++ programs on MS-Windows. Now, I am using Ubuntu Linux. How can I compile a C or C++ program on Linux operating systems using bash Terminal application?

To compile a C or C++ program on any Linux distro such as Ubuntu, Red Hat, Fedora, Debian and other Linux distro you need to install:

Tutorial details
Difficulty level	Easy
Root privileges	No
Requirements	GNU C/C++ compiler
Est. reading time	2 minutes

1. GNU C and C++ compiler collection
2. Development tools
3. Development libraries
4. IDE or text editor to write programs

Step #1: Install C/C++ compiler and related tools

If you are using Fedora, Red Hat, CentOS, or Scientific Linux, use the following yum command to install GNU c/c++ compiler:
# yum groupinstall ‘Development Tools’
If you are using Debian or Ubuntu Linux, type the following apt-get command to install GNU c/c++ compiler:
$ sudo apt-get update
$ sudo apt-get install build-essential manpages-dev

Step #2: Verify installation

Type the following command to display the version number and location of the compiler on Linux:
$ whereis gcc
$ which gcc
$ gcc —version
Sample outputs:

Fig. 01: GNU C/C++ compilers on Linux

How to Compile and Run C/C++ program on Linux

Create a file called demo.c using a text editor such as vi, emacs or joe:

How do I compile the program on Linux?

Use any one of the following syntax to compile the program called demo.c:

In this example, compile demo.c, enter:

If there is no error in your code or C program then the compiler will successfully create an executable file called demo in the current directory, otherwise you need fix the code. To verify this, type:
$ ls -l demo*

How do I run or execute the program called demo on Linux?

Simply type the the program name:
$ ./demo
OR
$ /path/to/demo
Samples session:

Animated gif 01: Compile and run C and C++ program demo

Compiling and running a simple C++ program

Create a program called demo2.C as follows:

To compile this program, enter:

To run this program, type:

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How do I generate symbolic information for gdb and warning messages?

The syntax is as follows C compiler:
cc -g -Wall input.c -o executable
The syntax is as follows C++ compiler:
g++ -g -Wall input.C -o executable

How do I generate optimized code on a Linux machine?

The syntax is as follows C compiler:
cc -O input.c -o executable
The syntax is as follows C++ compiler:
g++ -O -Wall input.C -o executable

How do I compile a C program that uses math functions?

The syntax is as follows when need pass the -lm option with gcc to link with the math libraries:
cc myth1.c -o executable -lm

How do I compile a C++ program that uses Xlib graphics functions?

The syntax is as follows when need pass the -lX11 option with gcc to link with the Xlib libraries:
g++ fireworks.C -o executable -lX11

How do I compile a program with multiple source files?

The syntax is as follows if the source code is in several files (such as light.c, sky.c, fireworks.c):
cc light.c sky.c fireworks.c -o executable
C++ syntax is as follows if the source code is in several files:
g++ ac.C bc.C file3.C -o my-program-name
See gcc(1) Linux and Unix man page for more information.

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Comments on this entry are closed.

thank you so much ur solution gave a relief…
it made my gcc command to work

Very nice article…..

In Fig. 01, you did “whereis” twice. Shouldn’t it be “which” the second time? Thanks for the tut though. Big fan!

Another mistake, please change the following comment:
## assuming that executable-file-name.c exists ##
to
## assuming that program-source-code.c exists in the current directory ##

how to compile a program that use math functions and other things?

For the sake of supplying an example, let’s say you want to use the cosine function. This is supplied in the Linux math library. The cosine function is called ‘cos()’. Similarly, the sine function is called ‘sin()’.

First, to find information about how to use them, type “man cos” in a terminal session. This gives you the manual page for the cosine function. The output from ‘man’ may vary for your system, but it likely tells you three things: 1. first, include the math.h header, 2. cos() takes a ‘double’ as its argument and it returns a double as its output, 3. to build your program, tell the C compiler to include the math library (-lm).

Here’s a sample program that does all of this:

Love it!
Thank you. I have a trouble in doing step 1 and 2. But they are fixed.

thank u ,
need pdf of the commands guide to access the c/c++/java.

to compile and run a c++ program in ubuntu follow these simple steps:
1 open terminal window.
2 type “gedit” .
3 A gedit window will appear whereyou can write your program.
4 save your program as “filename.cpp” on desktop, “.cpp” is compulsory.
5 open terminal again and type “cd Desktop”.
6 In second line type “g++ filename.cpp”.
7 Type “./a.out”.
NOW YOUR WILL RUN.

very nice to your step.
thanks

Thanks! This article really helped me to find the GNU compiler in a Linux Operating System and showed me how to compile a C program.

dear sir,
what is the procedure to run .cpp program in linux distro debian 5 ?

just about to get around to learning c along with teaching my sons it. i had no idea where to start, the first page i checked is a bumper bonanza.

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How to Write and Run a C Program in Linux

Linux is becoming programming heaven for developers, being an open-source and free operating system. Turbo C compiler is already an old approach to compile programs so let us programmers move to Linux for a new programming environment. In this article, we will explain how to write, compile, and run a simple C program. This will serve as a basis for you to move to more complicated and useful C programs that you can write and execute on Linux.

We have run the steps and commands mentioned in this article on a Ubuntu 20.04 LTS system but it will work on other versions like Ubuntu 18.04 or distributions like Debian 10 in the exact same way.

We will be using the Linux command-line tool, the Terminal, in order to compile a simple C program. To open the Terminal, you can use the Ubuntu Dash or the Ctrl+Alt+T shortcut.

Step 1: Install the build-essential packages

In order to compile and execute a C program, you need to have the essential packages installed on your system. Enter the following command as root in your Linux Terminal:

You will be asked to enter the password for root; the installation process will begin after that. Please make sure that you are connected to the internet.

Step 2: Write a simple C program

After installing the essential packages, let us write a simple C program.

Open Ubuntu’s graphical Text Editor and write or copy the following sample program into it:

Then save the file with .c extension. In this example, I am naming my C program as sampleProgram.c

Alternatively, you can write the C program through the Terminal in gedit as follows:

This will create a .c file where you can write and save a program.

Step 3: Compile the C program with gcc Compiler

In your Terminal, enter the following command in order to make an executable version of the program you have written:

Make sure your program is located in your Home folder. Otherwise, you will need to specify appropriate paths in this command.

Step 4: Run the program

The final step is to run the compiled C program. Use the following syntax to do so:

You can see how the program is executed in the above example, displaying the text we wrote to print through it.

Through this article, you have learned how to write, compile and run a simple C program in Linux. All you need is the essential packages and the right skills to make you a programming guru in Linux!

Karim Buzdar

About the Author: Karim Buzdar holds a degree in telecommunication engineering and holds several sysadmin certifications. As an IT engineer and technical author, he writes for various web sites. You can reach Karim on LinkedIn

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Making your own Linux Shell in C

To know more about what a shell is, click here.

We all use the built in terminal window in Linux distributions like Ubuntu, Fedora, etc. But how do they actually work? In this article, We are going to handle some under the hood features and algorithms what actually work inside a shell. All Linux operating systems have a terminal window to write in commands. But how are they executed properly after they are entered?
Also, how are extra features like keeping the history of commands and showing help handled? All of this can be understood by creating your own shell.

The Basics

After a command is entered, the following things are done:

1. Command is entered and if length is non-null, keep it in history.
2. Parsing : Parsing is the breaking up of commands into individual words and strings
3. Checking for special characters like pipes, etc is done
4. Checking if built-in commands are asked for.
5. If pipes are present, handling pipes.
6. Executing system commands and libraries by forking a child and calling execvp.
7. Printing current directory name and asking for next input.

For keeping history of commands, recovering history using arrow keys and handling autocomplete using the tab key, we will be using the readline library provided by GNU.

Implementation

To install the readline library, open the terminal window and write

It will ask for your password. Enter it. Press y in the next step.

• Printing the directory can be done using getcwd.
• Getting user name can be done by getenv(“USER”)
• Parsing can be done by using strsep(“”). It will separate words based on spaces. Always skip words with zero length to avoid storing of extra spaces.
• After parsing, check the list of built-in commands, and if present, execute it. If not, execute it as a system command. To check for built-in commands, store the commands in an array of character pointers, and compare all with strcmp().
  Note: “cd” does not work natively using execvp, so it is a built-in command, executed with chdir().
• For executing a system command, a new child will be created and then by using the execvp, execute the command, and wait until it is finished.
• Detecting pipes can also be done by using strsep(“|”).To handle pipes, first separate the first part of the command from the second part. Then after parsing each part, call both parts in two separate new children, using execvp. Piping means passing the output of first command as the input of second command.
  1. Declare an integer array of size 2 for storing file descriptors. File descriptor 0 is for reading and 1 is for writing.
  2. Open a pipe using the pipe() function.
  3. Create two children.
  4. In child 1->
  5. In child 2->
  6. Wait for the two children to finish in the parent.

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