Basic Fundamentals of "C"

1. Subject code: 2110003
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3. History of ‘c’
Features of ‘c’
Structure of program
Header files
Main function
Data type
Constant
Variables
Operators
Input/output
C preprocessor
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 C is developed by Dennis Ritchie
 C is a structured programming language
 C supports functions that enables easy maintainability of
code, by breaking large file into smaller modules
 Comments in C provides easy readability
 C is a powerful language

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 Important feature of ‘C’ language is it is portable, by
portability we mean that the program can be run on any
hardware machine.
 It supports modular programming.
 It supports bit-wise operations.
 It is known as structured programming language.

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 Documentation Section //optional
 Link section //optional
 Defining section //optional
 Global declaration section //optional
 Main function section //Must
 {
 Declaration part
 Executable part.
 }
 Sub program section //optional
 Function 1
 Function 2
 .
 .
 Function n

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 The files that are specified in the include section is called as
header file
 These are precompiled files that has some functions defined in
them
 We can call those functions in our program by supplying
parameters
 Header file is given an extension .h
 C Source file is given an extension .c

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 This is the entry point of a program
 When a file is executed, the start point is the main function
 From main function the flow goes as per the programmers
choice.
 There may or may not be other functions written by user in a
program
 Main function is compulsory for any c program

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A data type in a programming language is a set
of data values having predefine characteristics.
there are three classes of data types:
Data Type
Primitive derived user define

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 Primitive data types
int, float, double, char
 Aggregate data types
Arrays come under this category
Arrays can contain collection of int or float or char or
double data
 User defined data types
Structures and enum fall under this category.

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 The ‘C’ language supports following types of
constants:
Numeric constants (5, 15, 3.6, -5.4 etc)
Non-numeric constants
 Character constants (‘B’ , ‘a’ , ‘?’ , ‘5’ , ‘+’ etc)
 String Constants (“Computer”, “XYZ”, “-5.4” etc)

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 a Bell
 b Back space
 f Form feed
 n New line
 r Carriage return
 t Horizontal tab
 v vertical tab
 ’ single quote
 ” Double quote
 ? Question Mark
 Backslash
 0 Null

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 Variables are the identifiers whose value changes as opposite
to constants.
 As variable is an identifier, all the rules for naming an
identifier applies to variables also.
 Should not be a reserved word like int etc..
 Should start with a letter or an underscore(_)
 Can contain letters, numbers or underscore.
 No other special characters are allowed including space
 Variable names are case sensitive
 A and a are different.

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 Arithmetic (+,-,*,/,%)
 Relational (<,>,<=,>=,==,!=)
 Logical (&&,||,!)
 Bitwise (&,|)
 Assignment (=)
 Compound assignment(+=,*=,-=,/=,%=,&=,|=)
 Shift (right shift >>, left shift <<)

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 Input
scanf(“%d”,&a);
Gets an integer value from the user and stores it under
the name “a”
 Output
printf(“%d”,a);
Prints the value present in variable a on the screen

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 All preprocessor directives begin with #
 Possible actions
Inclusion of other files
Definition of symbolic constants & macros
Conditional compilation of program code
Conditional compilation of preprocessor directives

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