Online C Compiler

Online C Compiler

An Online C Compiler is a software tool that enables developers to write, compile, and execute C code online without needing a local compiler. It provides a web-based interface that empowers users to write and test their code in a browser without local installation and configuration. Moreover, online C compilers provide diversified features, such as saving projects, providing program input at runtime, and supporting multiple languages. 

Like any other compiler, an online C compiler converts your high-level C code to machine-level code that the computer can understand. It scans your code line by line to check for syntax, semantics, and other errors that may cause your program to crash or behave unexpectedly.

Intellipaat’s online C and C++ compiler and is the perfect tool for developers who want to write and test their C code seamlessly. With Intellipaat’s online C compiler, you can write your C code directly in the browser or copy and paste your existing code into the compiler. 

One of the main advantages of using an online C compiler provided by Intellipaat is that you don’t need to install any software on your local machine.

Working of the C Compiler

The following are some pertinent instructions for using the online C compiler:

  • Sign In: A sign-in is necessary to access the compiler’s features. Although running your code without logging in is feasible, it is recommended to sign in to make use of the compiler’s advanced capabilities. A pop-up window will appear by clicking the button in the top right corner.
  • Code Editor: Compose your code in the code editor, which provides syntax highlighting for enhanced readability.
  • RUN: Once the appropriate compiler version is selected, users can write C code in the editor and execute a C program by clicking the ‘RUN’ button.
  • SAVE: Use the ‘SAVE‘ button at the webpage’s top right corner to preserve your C code. The stored codes can be accessed using the web page’s ‘MY SNIPPETS' button.
  • Stdin & stdout: Users can utilize the compiler’s Standard Input (stdin) console to feed input to the C code while the code output appears on the compiler’s Standard Output (stdout).
  • SAVE: The saved programs can be publicly shared, making them available to all or privately accessible only to the code owner.
  • FORK: Public code snippets can be forked or downloaded using the ‘FORK’ button in the’ NEW‘ section. After forking a code, one can reuse it according to their requirements.
  • Share: If you require to share your code with others, Intellipaat’s compiler allows you to do so in a read-only format. To share your code, click the ‘SHARE' button in the web page’s top right corner.

What is the C Language?

Dennis Ritchie developed the C programming language during his tenure at Bell Labs in the 1970s. C is a high-level language that can produce efficient code for various hardware systems. One of C’s defining features is its structure, which allows programmers to create reusable functions and modules for their programs. 

C has been widely used in developing operating systems, device drivers, database systems, and other software applications. 

Syntax in C

Basic programming components like variables, data types, operators, control structures, functions, and arrays are all part of the C syntax.

Please find the following list of basic syntaxes for writing C programs that a C compiler can execute:

  • Syntax of Loops in C:

Loops in C are used to execute a code block repeatedly until a certain condition is met. The three types of loops are for, while, and do-while. Each loop has a specific syntax, but they all specify the condition for repetition and the code to be executed within the loop.

The syntax of the for loop in C is as follows:

for (initialization; condition; increment/decrement) {
    // code to be executed repeatedly

The syntax of the while loop in C is as follows:

while (condition) {
    // code to be executed repeatedly

The syntax of the do-while loop in C is as follows:

do {
    // code to be executed repeatedly
} while (condition);


  • The ‘initialization’ statement is executed only once before the loop starts and is used to initialize the loop variable.
  • ‘Condition’ is a Boolean expression that is assessed before each iteration. The loop keeps running if the condition is true. The loop ends if the condition is false. 
  • At the end of each iteration, the ‘increment/decrement’ statement is executed to modify the loop variable.
  • The code within the curly braces ‘{}’ is the code block executed repeatedly as long as the condition is true.
  • Syntax of Arrays in C:

An array in C is a collection of elements of the same data type stored in contiguous memory locations. It is declared with a data type, array name, and size, and elements can be accessed using their index. Initialization can be done when declaring the array.

The syntax to declare a one-dimensional array in C is as follows:

data_type array_name[row_size][column_size];


  • Here ‘data_type‘ refers to the specific type of data associated with each individual element within the array. The term ‘array_name‘ represents the designated name given to the array, while ‘array_size‘ indicates the total count of elements contained within the array. 

The syntax to declare a two-dimensional array in C is as follows:

data_type array_name[row_size][column_size];


  • The data_type represents the specific type of data that each element holds within a two-dimensional array. Meanwhile, array_name is used to identify the array itself, row_size indicates the total number of rows present, and column_size refers to the count of columns within the array.
  • Syntax of Functions in C:

In the C programming language, a function is formed by defining its return type, assigning it a unique name, and specifying any inputs it requires. Inside the function body, you will find the step-by-step instructions that carry out the desired task and, if necessary, a ‘return’ statement to provide a meaningful output.

In C, functions are generally classified into two types:

  • Built-in or library function- These are pre-existing functions that are readily available and can be used in any program. These functions have specific roles, such as presenting information on the screen using printf() or gathering user input using scanf().
  • User-defined functions- These functions can be used everywhere in the application to achieve their objectives because they are created using the syntax that was previously stated.

The syntax for defining a function in C is as follows:

return_type function_name(parameter_list) {
    // code to be executed
    return value;


  • Here, “return_type” refers to the type of data that a function will give back as a result. “function_name” is simply the name given to a specific function, while “parameter_list” represents a list of inputs or values that are passed to that function.
  • The actual code or instructions for the function are enclosed within curly braces {}. These instructions dictate what the function will do and how it will accomplish a particular task.
  • When we use the “return” statement within a function, it defines that the function will provide a specific value as output. This value should match the specified “return_type.” However, if a function doesn’t need to return any value, we can use “void” as the return type, and the “return” statement can be omitted.
  • To execute or use a function, we need to call it by its name followed by parentheses (). We can pass any required arguments or values to the function within these parentheses.

How Do You write a C program?

When creating a program in the C programming language, the initial step involves defining the main() function. This function acts as the entry point for the program’s execution. To utilize input and output functionalities, the “stdio.h” library needs to be included. The main() function conventionally has an integer return type, and it often returns 0 to indicate that the program was executed successfully.

Here’s an example of a basic C program:

#include <stdio.h>
int main() {
    printf("Welcome to INTELLIPAAT!");
    return 0;


  • This program uses the ‘printf()’ function to display the message “Welcome to INTELLIPAAT!” on the screen. 
  • The ‘return 0;’ statement indicates that the program has been successfully executed.

How Do You Compile and Run the C Program?

You can use the online compiler available on Intellipaat’s platform to write, compile, and run a C program. Within the provided editor, you can write your code. To initiate the compilation and execution, simply click the ‘RUN’ button. The output generated by the C program will be displayed on the standard output console for your convenience.

Additional Resources

C Programming Tutorial – Learn C Programming from Experts