C Overview

What is C?⁣

• Since the late 19th century, C has been a popular programming language for general-purpose use.
• C language was developed by Dennis M. Ritchie at bell laboratory in early 1970s⁣
• Its applications are very diverse. It ranges from developing operating systems to databases and all.⁣     It is system programming language used to do low level programming (e.g., driver or kernel)
• Even if it’s old, it is still a very popular programming language.⁣
• As the whole UNIX operating system was written in C, it has a strong association with the operating system⁣
• C has also been used widely while creating iOS and Android kernels.⁣
• MySQL database is written using C.⁣
• Ruby and Pearl are mostly written using C.⁣
• Most part of Apache and NGINX is written using C.⁣
• Embedded Systems are created using C⁣

 

Why should we learn C/ Features of C?

• As mentioned above, it is one of the most popular programming languages in the world.
• Learning any other popular programming language such as Python or C++ becomes a cakewalk already if you know C.
• C is a flexible language and that gets proven by the fact that it can be used in a variety of applications as well as technologies.
• C is very fast when compared to other programming languages be it Java or Python.
• C takes only significant CPU time for interpretation. That is why a lot of Python libraries such as NumPy, pandas, Scikit-learn, etc. are built using C.
• Being close to Machine language, some of its functions include direct access to machine-level hardware APIs.

• It is a structural language (Follows a specific Structure) /Compiled language this point should be added

• It is procedural programming language (POP) Procedurall Programming is the use of code in a step-wise procedure to develop applications. 

 

How is it different from C++?

• The syntax of C++ is almost identical to that of C, as C++ was developed as an extension of C.
• In contrast to C, C++ supports classes and objects, while C does not.
• C gives most of the control to the hand of users. Things like memory allocation and manipulation are totally in the hands of the programmer. Being a flexible language, it provides more access to the programmer because of which it is more efficient.

• .C is POP(procedure oriented programming) whereas c++ is OOP(Object oriented programming)

 

Getting Started with C

Requirements before you start

• To start using C, you need two things:
• A text editor, like Notepad, or an IDE, like VSCode to act as a platform for you to write C code
• A compiler, like GCC to translate the C code you have written which is a high-level language into a low-level language that the computer will understand.

 

What is an IDE?

• IDE stands for an Integrated Development Environment.
• It is nothing more than an enhanced version of a text editor that helps you write more efficient and nicer code.
• It helps to differentiate different parts of your codes with different colors and notifies you if you are missing some semicolon or bracket at some place by highlighting that area.
• A lot of IDEs are available, such as DEVC++ or Code Blocks, but we will prefer using VS Code for this tutorial series.

 

Installing VSCode

• Visit https://code.visualstudio.com/download
• Click on the download option as per your operating system.
• After the download is completed, open the setup and run it by saving VS Code in the default location without changing any settings.
• You will need to click the next button again and again until the installation process begins.

 

What is a Compiler?

• A compiler is used to run the program of a certain language which is generally high-level by converting the code into a language that is low-level that our computer could understand.
• There are a lot of compilers available, but we will proceed with teaching you to use MinGW for this course because it will fulfill all of our requirements, and also it is recommended by Microsoft itself.

 

Setting up the compiler

• Visit https://code.visualstudio.com/docs/languages/cpp
• Select C++ from the sidebar.
• Choose “GCC via Mingw-w64 on Windows” from the options shown there.
• Select the install sourceforge option.
• After the downloading gets completed, run the setup and choose all the default options as we did while installing VS Code.

 

Setting Path for Compiler

• Go to the C directory. Navigate into the Program Files. Then, open MinGW-64. Open MinGW-32. And then the bin folder. After reaching the bin, save the path or URL to the bin.
• Then go to the properties of ‘This PC’.
• Select ‘Advance System Settings’.
• Select the ‘Environment Variable’ option.
• Add the copied path to the Environment Variable.
• And now,  you can visit your IDE and run your C programs on it. The configuration part is done.

 

Basic Structure & Syntax

Programming in C involves following a basic structure throughout. Here’s what it can be broken down to.

• Pre-processor commands
• Functions
• Variables
• Statements
• Expressions
• Comments

Pre-processor commands

Pre-processor commands are commands which tell our program that before its execution, it must include the file name mentioned in it because we are using some of the commands or codes from this file.

They add functionalities to a program.

One example could be,

#include <math.h>

We include math.h to be able to use some special functions like power and absolute. #include<filename.h> is how we include them into our programs.

Detailed explanations of everything else in the structure will follow in the later part of the tutorial.

 

Header files:

* Collection of predefined/built in functions developed

•     It is always declares on heading side of program hence it is called header file

•     It is identified with the extension(.h)

•     It gets installed while installing IDE(integrated development environment)

•     It stores functions as per their categories hence they are called library

Syntax

An example below shows how a basic C program is written.

Declaration of header file   		//name of the header files of which functions are been used
main()	                           /*it is called main function which stores the execution of program*/
{	                                              //start of the program
              //program statements
}                                                //end of the program

• Here, the first line is a pre-processor command including a header file stdio.h.
• C ignores empty lines and spaces.
• There is a main() function then, which should always be there.

 

A C program is made up of different tokens combined. These tokens include:

• Keywords
• Identifiers
• Constants
• String Literal
• Symbols

 

Keywords

Keywords are reserved words that can not be used elsewhere in the program for naming a variable or a function. They have a specific function or task and they are solely used for that. Their functionalities are pre-defined.

One such example of a keyword could be return which is used to build return statements for functions. Other examples are auto, if, default, etc.

Whenever we write any keyword in IDE  their colour slightly changes and it looks different from other variables or functions for example in turbo c all keywords are turns into white colour .

 

Identifiers

Identifiers are names given to variables or functions to differentiate them from one another. Their definitions are solely based on our choice but there are a few rules that we have to follow while naming identifiers. One such rule says that the name can not contain special symbols such as @, -, *, <, etc.

C is a case-sensitive language so an identifier containing a capital letter and another one containing a small letter in the same place will be different. For example, the three words: Code, code, and cOde can be used as three different identifiers.

Rules for naming identifier-

1. One should not name any identifier starting with numeric value or symbol. It should start only with underscore or alphabet 
2. They should not contain space
3. Giving logical names is recommended as per our program

Constants

Constants are very similar to a variable and they can also be of any data type. The only difference between a constant and a variable is that a constant’s value never changes.  We will see constants in more detail in the upcoming tutorial.

String Literal

String literals or string constants are a sequence of characters enclosed in double quotation marks. For example,  “This is a string literal!” is a string literal. C method printf() utilizes the same to format the output.