Lecture 3 CP - II.ppt

7/28/2019 Lecture 3 CP - II.ppt

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Data Types & Storage Classes


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Datatypes

Data types indicate the type of data that a variable can hold

It may be numeric or non numeric

ANSI C supports three classes of data types:

1. Primary (or fundamental) data types

2. Derived data types (arrays, functions, structures andfunctions)

3. User-Defined data types

PRIMARY DATA TYPES:

All C compilers support five fundamental data types namely:

1. int

2. float3. char

4. double

5. void


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Primary Data types in CPRIMARY DATA TYPES

void

Integral Type

Integer Character

Floating point Type

char

signed char

unsigned char

float double Longdouble

Signed unsigned type

Int unsigned int

short int unsigned short intlong int unsigned long int


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PRIMARY DATATYPES IN C

A look on data type, keyword and their sizes in bytes

Types Keyword Size (in bytes)

Integer

Real

Double

Characternon-specific

int

float

double

charvoid

2

4

8

1


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int:

-It is reserved word that indicates an integer number

- It is a sequence of digits without decimal point- The range of int depends on the word length of the computer

Ex: For 8-bit computer it is -128 to 127

For 16-bit computer it is -32,768 to +32,767

Following are some valid and invalid integers:

Valid Invalid

-248

44042

27246

+1996

0

3,333

-34.0+3,468.3

9999999 (out of range)


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Float: It is a keyword to indicate a floating point number

They can expressed either in decimal form or scientific notation Scientific notation is chosen when the given data is too big or too

small

This scientific notation is also called as a MANTISSA-EXPONENTnotation

Following are valid and invalid floating point numbers:

Valid Invalid

-236.238

2.63238 E + 02

0.0263238 E + 04

26323.8 E -02

0,0

-2.2.2

- + 22.22


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Char: It is a keyword to indicate a floating point number

The data may be a character constant or a string constant

A character constant can be defined as any single characterenclosed within a pair of apostrophes

Ex : a, p, $, 2 etc.,

Each character constant has an integer value and is given by theASCII character set

Character constant ASCII value

A

B

Z

az

0

9

&

65

66

90

97

122

48

57

38


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Char:

A string constant is defined as a sequence of

printable ASCII characters placed between

the double quotes.

Ex: computer , Bangalkot , Hello ,Rupees , Y2K etc.,


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PRIMARY DATA TYPES IN C

Double: It is a keyword to indicate a double precision floating

point number

It is used for accuracy of data

The float usually stores a maximum of 6 digits after the

decimal point where as double stores 16 significant digitsafter the decimal point

Ex: 234.0000000000000000

Void:

The void type has no values This is usually used for specify the type of functions

This type of function called void does not return anyvalue to the calling function


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DERIVED DATA TYPES IN C

Primary data types can be used only to handle

limited amount of data For large volumes of data, we need powerful data

types which resolves many issues such as reading,processing and printing

Those data types are treated as derived datatypes . They are:

ARRAYS

STRUCTURE FUNCTIONS

POINTERS


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USER-DEFINED DATA TYPES IN C

C supports a feature called type definition that

allows users to define an identifier that wouldrepresent an existing data type.

The main advantage of typedef is we can createmeaningful data types which increases the

readability of a programSyntax: typedef type identifier;

EX: typedef int units;

typedef float marks;

Now, units symbolizes int and marks symbolizes floatthereby we can write

units batch1, batch2;

marks name1[50], name2[50];


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USER-DEFINED DATA TYPES IN C

Another user defined data type is ENUMERATED DATATYPE

This is used to declare variables that can have one of the

values enclosed within braces

Syntax: enum identifier { value1, value2,.valuen }; It automatically assigns integer digits beginning with 0 to all

enumeration constants

The automatic assignment can be overridden by defining

explicitlyEx:enum day { Monday, Tuesday, .. Sunday };

EX:enum day { Monday =1, Tuesday =2 ,..};Explicitly


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Datatype Range Bytes Format Specifier

int -32,768 to +32767 2 %d

Short signed int -32,768 to +32767 2 %d

Short unsigned int 0 to 65535 2 %u

Long signed int -2,147,483,648 to

+2,147,483,64

8

4 %d

long unsigned int 0 to 4294967295 4 %lu

Signed char -128 to +127 1 %c

Unsigned char 0 to 255 1 %c

Float 3.4e-38 to 3.4e+38 4 %f

Double 1.7e-308 to 1.7e+308 8 %lf

Long double 3.4e-4932 to 1.1e+4932 10 %LF


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/* Program to demonstrate data types*/ #include

main()

{int I = 10;

float f = 20.5;

double d = 30.005e25;

char s[20] = ICFAITECH;

char c = a:

printf(%d is integer value\n, i);

printf(%f is a floating point\n, f);

printf(%e is a double value\n, d);

printf(%s is a string\n, s);printf(%c is a Character\n, c);

}


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Output

10 is integer value

20.500000 is a floating point

3.000500e+26 is a double value

ICFAITECH is a string

a is a character


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// signed & unsigned type modifiers

#include

main()

{

signed int a = 10569;

unsigned int b = 56000u;

unsigned c = 56645;

Printf(signed int a = %d, a);

Printf(\n unsigned int b = %u, b);Printf(\n unsigned int c = %u, c);

}


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//Example

#includemain()

{

double a = 10.00776e123;printf(%g\n,a);

printf(%e\n,a);

printf(%lf\n,a);}


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STORAGE CLASSES

Storage classes provides information regarding the

location and visibility of variables They are very much useful in multifunction and

multi file programs

C provides a variety of storage class specifiers that

can be used to declare the scope and lifetime of avariable

Some of them are : auto (Default)

registerstatic

extern


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STORAGE CLASSES

Ex : int m; function1()

main() {

{ int i;

int i; float sum;float balance; ..

.. }

function1();}


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Lecture 3 CP - II.ppt