The C PROGRAMMING LANGUAGE: CHAPTER 01

C Programming Language is one of the oldest Programming Language. C was developed by Dennis Ritchie in 1972, USA. It is used to program a wide variety of system, major parts of WINDOWS, LINUX and other operating systems are written in C. It also helps us to write driver programs for devices like Tablets, printers etc. Embedded systems are programmed by using C language, where programs need to run faster in limited memory (microwave, cameras etc.). C helps in development of games an area where latency is very important i.e. computer has to react quickly on user input.

We have seen the usage of C programming language and the importance of it still if u want to know that why you should prefer Coding language read our blog: Coding Language : A Strange Paradise of future!

In the very beginning we need to understand about VARIABLES, CONSTANTS & KEYWORD that are used in C.

VARIABLES

variables are data-containers used to hold one or more values. Instead of repeating these values in multiple places in your code, variables hold the results of a calculation, database call, results of a database query, or other value. Like in a kitchen, we have containers storing rice, sugar, salt etc. similar to that variables in C stores values of data. However, values of variables can be changed at any point of time.

For Example:

a=3; // a is assigned as 3

b=4.7; // b is assigned as 4.7

c= 'A' ; // c is assigned as 'A'

(We will learn about assignment operators in the upcoming chapters)

There are some rules for naming variables in C.

1. First character must be an alphabet or an underscore ( _ ).

2. No commas or blanks are allowed in names of variables.

3. No special symbol are allowed other than an underscore ( _ ).

4. Variable names are case sensitive.

Case sensitive : Differentiating between capital and lower case letters, it is treated differently depending on whether it is in capital or lower case text.

In order to enhance readability of our programs, we must create a meaningful variable names in our programs.

CONSTANTS

An entity whose value doesn't change is called as a constant. A variable is an entity whose value can be changed.

There are types of Constants.

Primarily, there are three types of constants.

1. Integer Constant ➝ 1, 6, -7, 9 etc.

2. Real Constant ➝ 33.2, 7.777, -8.9 etc.

3. Character Constant ➝ 'a', '$', '@' etc. (must be enclosed within single inverted commas)

KEYWORDS

These are reserved words, whose meaning is already known to the compiler.

There are 32 keywords available in C.

auto double int struct

break long else switch

case return enum typedef

char register extern union

const short float unsigned

continue signed for void

default sizeof goto volatile

do static if while

As we have seen variables, constants and keyword, now we will preceed to BASIC STRUCTURE OF A C PROGRAM.

But before that here's our first C program.

All C Program have to follow a basic structure. A C program starts with main function and executes instructions present inside it. Each instruction is terminated with a semicolon (;).

There are some rules which are applicable to all the C programs.

1. Every program's execution starts from main() function.

2. All the statements are terminated with semicolon (;).

3. Instructions are Case-sensitive.

4. Instructions are executed in the same order in which they are written.

COMMENTS

Comments are used to clarify something about us to add notes to our program.

There are two types of comments in C.

1. Single line comment:-

// This is a comment

2. Multi-line comment:-

This is an example

of multi-line comment

Comments in a C program are not executed and are ignored.

COMPILATION AND EXECUTION

A Compiler is a computer program which converts a C program into machine language so that it can be easily understood by the computer.

A C Program is written in plain text. This plain text is combination of instructions in a particular sequence. The compiler performs some basic checks and finally converts the Program into machine language so that it could be executed.

LIBRARY FUNCTIONS

C language has lots of valuable library function which is used to carry out certain tasks for instance printf function is used to print values on the screen.

printf ("This is %d", i);

%d for integers

%f for real values

%c for characters

we haven't seen the type of variable yet but now we will see what are its type.

1. Integer variable ➝ int a = 3 ;

2. Real variable ➝ float a = 7.7;

3. Character variables ➝ char a = 'B';

( \n = this is used for new line )