Online C Compiler

To start your programming journey you first need to understand what compilers are. Compilers are the computer software that converts your high-level source code to executable machine-level instructions made up of 0s and 1s, that can be understood by the computer.

Compilers scan the high-level code line by line and show different kinds of errors present in the code in the command line.

Scaler Topics online compiler supports the latest versions of C and, programmers can write, run, debug and share code snippets seamlessly.

It is one of the most robust & easy-to-use Online Compilers. Owing to the fact that it has a plethora of features to offer to the budding C programmers of today & extremely easy to get going, we’ve strived to create the best online C compiler.

Working of the C Compiler (IDE)

Scaler Topics provides us with one of the best C compilers that is easily operated and that supports multiple programming languages.

Given below are some of the steps of our Compiler which users might find helpful:

The first step is your need to Sign-In to use the features of this compiler. It is possible to run your code without signing in but you will not have a track to your previous codes here, so it's advisable to sign in to enjoy its cool features. Click on the button present at the top right corner and a window will appear.

  • Code Editor: Write code in the code editor (which has syntax highlighting for more code readability). For users who are logged into the Scaler Topics Platform, the total number of characters in their code can go up to five thousand characters. For non Scaler Topics Users, their C code can have up to five hundred characters.
  • RUN: In order to run a C program, a user can write C code in the editor and then click on the ‘RUN’ button after selecting the appropriate compiler version.
  • SAVE: The C code written in the editor can be saved by clicking on the ‘SAVE’ button on the top right corner of the webpage. The saved codes can be accessed using the ‘MY SNIPPETS ’ button of the webpage.
  • STDIN & STDOUT: In order to feed input to the C Code, users can use the Standard Input (stdin) console of our compiler and the output of the code appears on the Standard Output (stdout) of the compiler.
  • SAVE: The programs saved can be made public - available for all - or private - accessible to only the code owner.
  • FORK: Public code snippets can also be forked or downloaded in the ‘NEW’ section using the ‘FORK’ button. After forking a code, one can reuse it as per requirement.
  • SHARE: Now that you have your code ready, you might need to share it with people. Our compiler also supports sharing of code in Read-Only Format. This can be done using the ‘SHARE’ button on the top right corner of the webpage.


What is C language?

With an initial release in the year of 1972, the C language is one of the oldest general-purpose programming languages of today. It was developed by Dennis Ritchie at Bell laboratories for the UNIX operating system.

It is a procedural computer programming language that supports a plethora of features like structured programming, lexical variable scope, and recursion, with a static type system.

A lot of operating systems and databases, for instance, the UNIX operating system and Oracle and MySQL databases have been written in the C Programming language as it is extremely fast. It can also handle low-level activities and supports a variety of platforms.

Syntax in C

Please find below a list of basic syntaxes which can be used to write a c program and can be run using a gcc c compiler:

Syntax of Branching or Control Flow Statements


In order to do branching of your program on the basis of one or more conditions, the if-else statements can be used. The syntax of the if-else statement is given below.


At times there might be multiple conditions that need to be checked if one condition fails. For this, we can also use the if else-if else statements. The syntax for the same is given below:

switch case

If a lot of branching is required for your C program, then the if-else statements can make the code look ugly and less readable. To avoid this, we can use the switch statement. Given below is the syntax for the switch statement.


Syntax of Loops in C

In order to execute a set of C statements repeatedly, a loop can be used. Given below are the syntaxes of different types of loops in C:

for loop


while loop


do-while loop


Syntax of Arrays in C

If we need to store multiple elements of the same data type together, we can use the Array data structure of the C programming language. Arrays are stored in contiguous memory addresses and array values can be fetched using indices. The indexing in arrays ranges from 0 to size-1.

Arrays can be of any dimension in general. But the most popularly used arrays are one-dimensional and two-dimensional arrays. Given below is the syntax to declare an array.

Syntax to declare a One Dimensional Array:

Syntax to declare a Two Dimensional Array:

Syntax of Functions in C

If a piece of code needs to be reused again and again in different parts of our C program, the features of Functions in C can be used. A set of statements are written in functions, which can be called from various parts of the program. This increases the modularity of the code written and also supports code reusability.

Functions are of two types:

  • Library Functions: Library functions are those functions that are built-in in the C programming language. These are declared in the header files, for instance, printf(), scanf(), puts(), gets() etc., and can be included in our C code using the preprocessing directives. For example, the standard input and output files containing the functions for standard input and output can be included in our C code as follows: #include<stdio.h>
  • User-Defined Functions: User-defined functions are those functions that are written by C programmers based on the requirement of their logic.

Functions in C programs can be declared as follows:

Functions in C programs can be defined as follows:

Functions in C programs can be called from any part of the C code as follows:

How to write a C program?

In order to write a C program, one can refer to the previous section. The entry point of a C program is always the main() function. In order to include the standard input and output library functions, one can include the “stdio.h” library. The main() function usually has a return type as an integer. If the code runs successfully, a value of zero is returned. Given below is a sample C code to get you started with C programming:

How to compile and run the C program?

For the Scaler Topics online compiler, it is very easy to compile and run the C program. One can just write the code in the editor and then click on the ‘RUN’ button in order to run and compile it. The standard output console shows the output of the C program.

Additional Resources


  • Online IDE: IDE is an acronym for Integrated Development Environment. Online Integrated Development Environments help programmers code in various languages and run, compile and debug their codes online without having the need to download the respective programming compilers.
  • Compiler: In computing, a compiler is a computer program that is used to translate computer codes written in one programming language into another language.
  • Interpreter: Like Compilers, interpreters are also used to translate computer codes written in one programming language into another language. However, the difference between the two is that compilers compile the entire source code into machine code at once while interpreters convert the source code into machine code line by line.
  • Code Editor: A code editor is software used by programmers to code. Most code editors provide various features like syntax highlighting to make the code written on them more readable.
  • Coding Ground: Coding grounds are platforms that can be used to write and run codes written in various languages.