1.getting started with c

Getting Started
What you’ll learn:
1. Basic Structure of a C
Program
2. Basic Syntax of C language
3. Data Types
4. Defining Variables and
Constants
5. Console I/O

Getting Started
Basic Structure

Basic Structure
A C program basically consists of the following parts:
 Pre-processor Commands
 Functions
 Variables
 Statements & Expressions
 Comments

Character Set
 Letters: A-Z a-z
 Digits: 0-9
 Symbols: + - * / % = _ | ~ ^ / ? ! @ # $ & : ; “ ‘ ` , . < > () {} []
 ASCII symbols: 256 characters including the above ones.
 Unicode symbols: UTF-8 can represent all 1,114,112 Unicode characters.

Tokens
o Keywords
o Identifiers
o Literals
o Strings
o Punctuators
o Operators

Keywords
32 Keywords from C89
auto double int struct break else long switch
case enum register typedef char extern return union
const float short unsigned continue for signed void
default goto sizeof volatile do if static while
5 Keywords from C99
_Bool _Imaginary
restrict _Complex
inline
6 Keywords from C11
_Alignas _Atomic
_Noreturn _Alignof
_Generic _Static_assert

Identifiers
Rules for defining Identifiers
 It can only contain letters, digits, or an underscore.
 It should not start with a digit. It can start with a letter or an underscore.
 A keyword should not be used as an identifier.
 Since C is a case sensitive language so uppercase letters differ from lowercase ones.
Apple apple

Valid and Invalid Identifiers
 Valid Identifiers:-
VarName VAR2NAME _var11 var_name_11 int_100
 Invalid identifiers:-
var-name 11varname int var name $var_name

Literals
Literals are also called constants. We have following type of constants:
 Integer constant 1, -11, 0xC, 010
 Floating constant -32.56, 0.9787
 Character constant ‘a’, ‘1’, ‘#’

Strings
 String literal is a sequence of characters.
E.g. “Hello”
 It is terminated by ‘0’.
E.g. “Hello” will be represented as “Hello0” in memory.

Punctuators
 Square brackets [ ]
 Parenthesis ( )
 Curly Braces { }
 Comma ,
 Terminator ;
 Colon :
 Asterisk *
 Ellipses …
 Equal =
 Pre-processor #

Basic Operators used in C
 Arithmetic: + - * / %
 Assignment: = += -= *= /= %=
 Increment/Decrement: ++ --
 Relational: == <= >= < >
 Logical: ! && ||
 Conditional: ? :
and many more…

Data Types
Fundamental
 int
 float
 double
 char
 void
Derived
 Arrays
 Structure
many more ….

For integer types
MODIFIERS SIZE RANGE
Int 4 bytes -2147483648 to 2147483647
Unsigned int 4 bytes 0 to 4294967295
Signed int 4 bytes -2147483648 to 2147483647
Short int 2 bytes -32768 to 32767
Unsigned short int 2 bytes 0 to 65535
Signed short int 2 bytes -32768 to 32767
Long int 4 bytes -2147483648 to 2147483647
Signed long int 4 bytes -2147483648 to 2147483647
Unsigned long int 4 bytes 0 to 4294967295

For floating types
Float 4 bytes -3.4e-38
to +3.4e+38
Double 8 bytes -1.7e-308
to +1.7e+308
Long double 8 bytes -1.7e-308
to +1.7e+308

For character types
Char 1 byte 0 to 255
Unsigned char 1 byte 0 to 255
Signed char 1 byte -128 to +127

Getting Started
Variables and Constants

Variables
It refers to a storage location in the memory space whose value can be manipulated.
int a = 10;
a = 20;
10
20
value at
memory
location
data type
identifier
value
of the
variable
value
changed

Constants
It refers to a storage location in the memory space whose value is fixed.
const int a = 10;
a = 20;
10
10
value at
memory
location
data type
identifier
value
of the
variable
value
can’t be
changed
keyword

Console Input Output
 printf()
 scanf()

printf()
 Used to display formatted output on the console.
 Syntax:
printf(“Answer = %d”, i );
Format Specifier
Integer VariableFormatted Text

scanf()
 Used to take input from the console.
 Syntax:
scanf(“%d”, &i );
Format Specifier
Integer VariableAddress of Operator

1.getting started with c

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