C Tutorial



C Tutorial

History of C Language

C is one of the most efficient programming languages used to develop operating systems. It has many features that make C language easy to operate, even for beginners. It is mostly used in making software systems, application software and embedded system. 

The language was developed as a system implementation language in the early 1970s, which evolved from the typeless language BCPL. However, before learning about C language in depth, it is crucial to understand the background of C along with some important history associated with it. 

Let us take you through the history of C language and a brief timeline of C language. We will also discuss some of the best online language compilers for developers. 

Introduction to C Programming Language

C is a high-level programming language created in the early 1970s under the gudiance of Dennis Ritchie. Since then, it has become one of the most prominently used and influential programming languages globally. Known for its simplicity, efficiency, and versatility, C has been utilised for various applications, and its popularity can be attributed to its powerful features, such as low-level memory access, a rich set of operators, and a modular structure. 

C's portability allows it to run on various hardware platforms and operating systems. As a foundational language, C has influenced the development of numerous other programming languages and continues to be widely used in academic and industrial settings. Its relevance and widespread adoption make C an essential language for aspiring programmers.

History of C Programming Language

The father of programming languages is ‘ALGOL’, first introduced in 1960. ALGOL (Algorith Language) was initially used significantly in European countries, and it introduced the concept of structured programming to the people. In 1967, a new programming language came into force called ‘BCPL’, meaning Basic Combined Programming Language. 

BCPL was designed and developed as a general-purpose programming language by Martin Richards. After three years, another programming language was introduced in 1970 by Ken Thompson. It was known as ‘B’, which combined various features of ‘BCPL”. It was created using the UNIX operating system at AT&T and Bell Laboratories.

In 1972, Dennis Ritchie and Ken Thomspon developed a new programming language called ‘C’ at the Bell Laboratories, created from ‘ALGOL’, ‘BCPL’, and ‘B’. ‘C’ contains all these languages and much more, making it unique from the other programming languages. It is a powerful language which is associated with UNIX.

Initially, ‘C’ was limited to UNIX OS, but it gradually spread worldwide, and many compilers were released for cross-platform systems. 

The American National Standards Institute (ANSI) introduced voluntary standardization for C in 1989 to establish a standard for the language and ensure its consistency. Subsequently, this standard was approved by the International Standards Organization (ISO) in 1990, leading to the language being commonly referred to as "ANSI C". These standardisation efforts aimed to provide a stable foundation for C and facilitate its widespread adoption and compatibility across different environments.

Early Implementations and Language Standard

The C language was intended to build the foundation for the creation of UNIX. In early 1973, parts of ultramodern C had been completed, and the language and compiler were robust enough to rewrite the UNIX kernel in C for the PDP-11. The C language finally came into existence under the guidance of Dennis Ritchie between this period of 1969-1973, serving as a reference for language till the formal standard was established in the history of C language. 

Between 1973 and 1980, the C language underwent minor changes, including adding unsigned, long, union, and numerous types and enhancing structures. In 1983, the X3J11 committee, led by CBEMA, was formed to create a C standard. The committee's report, published in 1989 and known as ANSI 89, was later adopted by ISO as ISO/IEC 9899-1990.

A List of Programming Languages Developed Before C Language



Year of Development


International Group



Martin Richards



Ken Thompson


Traditional C

Dennis Ritchie



Kernighan and Ritchie



ANSI Committee



ISO Committee



Standardization Committee


The Problems of B Programming Language

While B had its strengths, it also faced several challenges and limitations. One of the major issues with B was its lack of data typing. Variables in B were not explicitly defined, leading to potential errors and difficulties in understanding the program's intended usage. B had limited support for structured programming constructs, making writing large and complex programs challenging. 

Another drawback was its inefficient implementation, as B programs relied heavily on interpreting and translating the source code during runtime, resulting in slower execution speeds than compiled languages. 

These limitations and shortcomings of B led to the subsequent development of the C programming language, which introduced stronger typing, enhanced syntax, and improved performance, making it a more robust and widely adopted programming language.

Standardization of C

In 1983, the X3J11 committee was formed by ANSI to standardize the C programming language. The resulting standard, ANSI X3.159-1989, was ratified in 1989 and published in 1990. It was later superseded by ISO/IEC 9899:1990, establishing it as an international standard. 

Updates and corrigenda have been made since then, with the current standard being ISO/IEC 9899:2018, commonly called C18. The titles "ANSI C" and "ISO C" are informally used to recognise the efforts of the standards community in unifying the language over the past thirty years.

How Does C Programming Language Work?

Since computers operate using binary code consisting of 1s and 0s, it is necessary to translate our human-readable language into machine-understandable instructions. In the context of the C programming language, this translation occurs through the process of compilation. 

When you write your code in C, it is transformed into an executable file. The C compiler then processes this file, which converts the entire code into machine code. This machine code is the low-level instructions the computer's processor can directly understand and execute during runtime. 

Here is an example of the basics of C programming language:

#include <stdio.h>

int main() {
  printf("Hello World!");
  return 0;
  /* We can also use getch(); as a terminating function instead of 0; */

This code example provides insights into how a C program operates:

  • The code begins with a preprocessor command, #include, which instructs the compiler to include the stdio.h header file. This header is necessary to use the standard input/output function printf() to print our message.

  • Next, the main function is initialized with the line "int main() {}". It serves as the program's entry point, where the execution starts.

  • Within the curly brackets "{}", we specify the actions we want the main function to perform. In this case, the printf() function displays the message "Hello World!".

  • A return statement indicates the program's end to the compiler. The line "return 0;" signifies the successful termination of the program. 

This is the fundamental demonstration of C’s power. We also use conditionals, control statements, and data structures for higher-level programming. 

C Basic Commands

Below are the basic commands in C programming language:

C Basic Commands



Before compiling a C program, the command "include stdio.h" is used to incorporate the standard input/output header file from the C library.

int main()

The main function serves as the starting point for the execution of a C program.


It indicates the beginning of the main function


Any content written within a C program's "/* */" command is disregarded during the compilation and execution processes.


It prints the output on the screen 


It is used for any character input from the keyboard


It terminated the main function and returns 0


It depicts the end of the main function

List of Popular Online Compilers

Here are some of the most popular online compilers that let you run C/C++ codes:

1. OnlineGDB C Compiler: This platform supports various programming languages. The web portal provides a clean UI and is comprehensive for beginners. You don’t have to create an account to run the codes.

2. Tutorialspoint Compiler: One of the most popular online compiler platforms with numerous offerings. All you have to do is create an account to share the code that you want to run through this compiler. However, it does not support the code links without sign-in. But it comes with a clean interface compared to other online Compilers.

3. Replit: It is a full-fledged compiler that offers premium features, supports other languages, and has a separate team offering. It can also be used for a professional purpose under the premium plan. After creating an account, it lets you facilitate more features of C language. 

4. Rextester: It is best to run the debug code and is one the simplest compiler for C/C++. You can switch the operations between dark and light themes and vertical/horizontal layouts.

5. OneCompiler: This is one of the best online compiler platforms that supports a wide range of programming languages. It comes with a neat interface and offers a great experience to the users. It also allows you to switch between light and dark themes. You will find a bunch of different tutorials, posts, and coding challenges that help you learn while you’re at C programming. 

Why Should You Learn C?

Here are some benefits of learning the C programming language:

  • It will help you understand how a computer works: With the help of C, you can understand and visualise the working of a system, such as allocation and memory management, their architecture, and overall concept. C lets you create complex and comprehensive programs and also teaches you how to write code that can be more efficient in C and other programming languages. 

  • Almost all other programming languages can interface with C: Programs such as JavaScript, Python, and Java can interface with C. The codes written in C can also be executed, and the program can be run on another computer. Moreover, C can be beneficial for communicating concepts and ideas in other languages due to its universal nature. 

  • You will be able to work with open-source projects: While there are numerous programming languages utilised in various applications, it is important to note that most of them were developed using C. Acquiring proficiency in C empowers individuals to engage in open-source projects, such as contributing to the development of Python, which has a far-reaching impact on millions of programmers globally. 

  • Makes learning other languages easier: Learning C programming makes other languages easier to understand as it is related to other programming languages. These languages typically share syntax, operators, control statements, etc. 

  • An efficient programming language: C contains 32 keywords, besides built-in functions and data types. It also consists of a library of functions that programmers can add, which allows access to all the features and functions. These properties make C language efficient and effortless while creating complex programs. 

Applications of C Programming

The C programming language finds extensive usage in various domains:

  • C is heavily employed in embedded systems.

  • It serves as a prominent language for developing system applications.

  • C is widely utilised for creating desktop applications.

  • Adobe relies on the C programming language to develop many applications.

  • The development of browsers and their extensions, such as Google's Chromium, heavily relies on C.

  • C is instrumental in building databases, with MySQL being a notable example.

  • C plays a significant role in compiler production.

  • C is widely adopted in Internet of Things (IoT) applications.


Wrapping up, the C programming language is one of the essential tools for developing various applications. It is the basic programming language that makes other languages easier to understand and gives you a good grasp of codes. 

While going through tutorials can help you learn all about C, upskilling with leading courses, like upGrad’s MS in Computer Science from Liverpool John Moores University can help you explore the vast possibilities it offers to its learners. 

Enroll now to kick start your journey with upGrad!


1. What is C language and its types?

C is a versatile programming language for developing diverse applications, initially designed for operating system development. The C language is extensively employed in creating the Unix kernel and its accompanying tools and libraries. 

2. What is the main function in C?

Every C program has a primary function that acts as the program's entry point, serving as the starting point for execution. It typically manages the program's flow by directing calls to other functions within the program.

3. What is the basic syntax for C language?

The fundamental structure of a C program includes header files, the main function, and program code. The main function is essential as it marks the starting point for program execution, without which the program will not initiate its execution.

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