introduction to c

2.  C is Programming Language
 Developed at AT & T’s Bell Laboratory in 1972
 Designed and Written by Dennis Ritchie
 Replaced more familiar language like PL/I,
ALGOL etc.
 Reliable, Simple and easy to use.

3.  Nobody can learn directly C++/ Java directly
 C++, C# or JAVA make use of object oriented
programming to organize program
 Major parts of popular OS like windows, Linux
are still written in C
 Common consumer devices like microwave
ovens, washing machines and digital cameras
program part is written in C
 Some of 3D computer games

6.  VARIABLES
• Variables is entity that may change
• Variable is nothing but the name given to the
memory cell
 CONSTANTS
• Constant is an entity that doesn’t change

7.  KEYWORDS
• “Reserved Words”
• Keywords are the words whose meaning has
already been explained to the C Compiler
• Keywords cannot be used as variable names.
• 32 Keyword available in C.

9.  Constant can be declared in the way we declare
variable
 But during declaration value need to be
assigned to declared contant name. Its value
cannot be modifeid in the program
 In another way, Constant is nothing but the
value that we assign to variable.

11.  An integer constant must have atleast one digit
 It must not have decimal point
 It can be either positive or negative
 If no sign precedes an integer constant, it is assumed
to be positive
 No commas or blanks are allowed within an integer
constant
 The allowable range for integer constant is -32768
to 32767 (assuming 16bit Compiler)

12.  An integer constant must have atleast one digit
 It must have decimal point
 It can be either positive or negative
 Default sign is positive.
 No commas or blanks are allowed within an
integer constant

13.  The mantissa part and exponent part should be
separated by a letter e or E
 The mantissa part can be positive or negative
 Default sign for mantissa is positive
 The exponent part must have atleast one digit
which must be a positive or negative integer.
Default sign is positive

14.  Any single alphabet, single digit or a single
special symbol enclosed within single inverted
commas.
 Both inverted commas should point to left

15.  Variable name is any combination of 1 to 31
alphabets, digits or underscores.
 The first character in the variable name must be
an alphabet or underscore
 No commas or blanks are allowed within
variable name
 No special symbol other than an underscore

16.  C compiler expects from user to specify type of
variable user want to use in program
 This declaration is done at the beginning of
program
 Eg. int a, float akc, char code

17.  Different types of data allowed to be used in C
language
 Primary data types are
o Integer
o Float
o Character
 Some modifiers are allowed in C which gives
multiple sub class of data types
 Such modifiers are like long, short, signed,
unsigned, double, long double etc..

18.  Character occupies 1 byte memory location
 Example for character variable declaration
 Signed character (Range is -128 to 127)
 Unsigned character (Range is 0 to 255)
 Format specifier is %c.

19. For 16 bit compiler
2^16=65536
So Range is -32768 to +32767
For 32 bit compiler
2^32=4294967296
So range is -2147483648 to 2147483648

20.  Integer
 Long
 Short
 Unsigned
 Signed
For 16 bit compiler
Int a; (2byte)
a= 32800
Will not work as it is above 32767

21. long int a; (4byte)
a= 32800
Will work as it is falls in the range of -2147483648
to 2147483648

22.  Signed
 Unsigned

23.  Float occupies 4bytes in memory
-3.4e38 to +3.4e38 (6 digits after decimal point)
 Double occupies 8bytes in memory
-1.7e308 to +1.7e308 (12 digits after decimal point)
 Long double occupies 10bytes in memory
-1.7e4932 to +1.7e4932 (19 digits after decimal
point)

24. DATA TYPE SIZE RANGE FORMAT
SPECIFIER
int 4byte -2147483648 to 2147483647 %d
unsigned int 4byte 0 to 4294967296 %u
long int/long 4byte -2147483648 to 2147483647 %ld
unsigned long int 4byte 0 to 4294967296 %lu
long long int 8byte -9223372036854775808 To
-9223372036854775807
%lld
short int/short 2byte -32768 to 32767 %hd
unsigned short int 2 byte 0 to 65535 %hu
float 4byte -3.4e38 to 3.4e38 %f
double 8byte -1.7e308 to 1.7e308 %lf
long double 12 byte -1.7e4932 to 1.7e4932 %Lf
char 1byte -128 to 127 %c
unsigned char 1byte 0 to 255 %c

25.  Assignment Operators
= is an assignment operator
• a=15
• a=b=c=15
• a+=15

26.  Auto Increment/ Decrement Operators
These operators are ‘++’, ‘--’,
• The operator ++ adds 1
• The operator –– subtracts 1
• Two types: Prefix and Postfix auto
increment/decrement
• Prefix a=5 b=5
b=++a
After Execution a=6 b=6

27.  Postfix
a=5 b=5
b=a++
After execution a=6 b=5

28.  + addition
 - subtraction
 * Multiplication
 / division
 % modulo

29.  ==
Checks if values of two operands are equal or not.
If yes then condition becomes true
 !=
Checks if values of two operands are equal or not.
If no then condition becomes true
 >
Checks value of left operand is more than right
operand. If yes then condition is true

30.  <
Checks whether right operand is more than left
operand. If yes then condition is true.
 >=
 <=

31.  AND &&
 OR ||
 NOT !
• AND and OR operators allow two or more
conditions to be combined in if statement.
• Not operator reverses the result of an
expression it operates on. The output is logical
value i.e. 0 or 1.

32.  AND &
 OR |
 1’s complement operator ~
 XOR operator ^
 Left shift operator <<
 Right shift operator >>

33.  Also called as Ternary Operator (?:)
Max=a>b?a:b

34.  One Expression may contain different
operators
 Precedence means the order in which the
operations are carried out for given
expression.
 Associativity comes into picture when
operators of same priority comes into
expression.

35. Hierarchy of Operators
! Logical Not
* / %
Arithmetic and
modulus
+ - Arithmetic
< > <=
>= Relational
== != Relational
&& Logical AND
|| Logical OR
= Assignment

36. printf(“Text to printed on output screen”);
e.g. printf(“WELCOME to DKTE”);
printf(“Text with format specifier”, variable list);
e.g. printf(“year is %d”, y);
printf(“Text with format specifier”, expression);
e.g. printf(“addition is %d”, a+4);

37.  scanf(“format specifier”, list of variable address);
 E.g
scanf(“%d”,&a);
scanf(“%c”,&d);

40. if (condition/expression)
{ statement1;
stetement2;
……..
}
 If only one statement present, then there is no
need of curly bracket. But though they are
present there won’t be an error.

41. if (condition/expression)
{ statement1;
statement2;
…….
}
else
{
Statement1;
Statement2;
….
}

42. if(condition/expression)
{ statement1;
……. }
elseif(condition/expression)
{ statement1;
…….}
elseif(condition/expression)
{statement1;
……}

43. If (condition)
{
if (condition)
{
statement1;
….
}
else
{
statement1
…..
}
else
{
Statement1
……
}

45. Syntax
while(condition)
{
statement1;
statement2;
………
}

46.  Syntax
do
{ statement1;
Statement2;……………………
} while(condition);

47.  Syntax
for (initial counter; test counter; increment counter)
{
statement1;
statement2;….
}

48. switch(integer expression)
{
case constant1:
statement;
case constant2:
statement;
case constant3:
statement;
default:
statement;
}

49. switch(integer expression)
{
case constant1:
statement;
break;
case constant2:
statement;
break;
case constant3:
statement;
break;
default:
statement;
}

51.  Array is a collective name given to group of
memory location containing similar data types.
 Array is a collection of similar elements.
 Similar elements could be all int, or all float or
all char, etc.
 Array of character is called as ‘string’.

52. int marks[30]
int salary[6]= {24,45,56,56,56,76}
int salary[]= {24,45,56,56,56,76}