Programming and Data Structures

The C Declarations 31

Basic Data Type

The basic data types supported by C are described with their size in bytes and ranges in Table 2.5.

Table 2.5 Basic data types of C with size and range

Data Type

Size in bytes Range

char

1

-128 to 127

unsigned char

1

0 to 255

signed char 1

-128 to 127

int 2 -32768 to 32767

unsigned in t 2 0 to 65535

signed in t 2

-32768 to 32767

short in t 2

-32768 to 32767

unsigned short in t

2 0 to 65535

signed short in t

2 -32768 to 32767

long in t

4 -2147483648 to 2147483647

signed long in t

4 -2147483648 to 2147483647

unsigned long in t

4 0 to 4294967295

float

4 3.4E-38 to 3.4E+38

double

8

1.7E -308 to 1.7E+308

long double

10

3.4E -4932 to 1.1E +4932

enun

2

-32768 to 32767

Derived Data Type

The derived data types are of the following types:

a) Pointers

b) Functions

c) Arrays

a) Pointers: A pointer is a memory variable that stores a memory address. Pointers can have any name

that is legal for other variables and it is declared in the same fashion like other variables but it is

always denoted by operator.

int *x;

float *f ;

char *y;

32 Programming and Data Structures

In the first statement' x ' is an integer pointer and it tells to the compiler that it holds the address of any

integer variable. In the same way ' f ' is a float pointer that stores the address of any float variable and

' y ' is a character pointer that stores the address of any character variable.

2.1 Write a program to use pointers.

# include <8tdio.h>

# Include <canio.h>

void xaainO

{

int x»2,*p;

clrscr {) t

print£(m\n Address of x -%u

P - & X f

printf (*\n Value of x«%d *,*p);

OUTPUT;

Address of x * 4096

Valueof x*2

Explanation In program 2.1 x is an integer variable and pis an integer pointer. Thefirstprintf ()

statement displays the address of variable x. The address of x is assigned to pointer p. The pointer

variables are always used to store address of another variable. The second statement displays the

value of x using pointerp. Fig. 2.3 explains pointers.

Fig. 2.3 Pointers

b) Functions: A function is a self-contained block or a sub-program of one or more statements that

perform a special task when called. Fig. 2.4 illustrates the function. In Fig. 2.4 f unA() and f unB () are

two user-defined functions. These are invoked from the body of main. After execution of f unA() and

funBO the program control returns back to the calling function main().

The C Declarations 33

Fig. 2.4 Functions

A simple program on function is described as follows.

22 Write a program to demonstrate user-defined functions.

# Include <conio.h>

# Include <stdio.h>

void m&in()

{

clrscr ();

void show (void);

show ();

}

void show()

{

printf ("\n In function 8ho*r()");

I

OUTPUT:

In function show ()

Explanation In the above program the function show () is defined. The function body contains only

one p rin t f () statement. When the function is executed a message is displayed.

c) Arrays: An array is a collection of elements of similar data types in which each element is located in

separate memory location. For example,

in t b [4];

34 Programming and Data Structures

The statement on the previous page declares an array b [ ] which can hold four integer values. The

following program illustrates use of an array.

13 Write a program to declare, initialize an array. Display the elements of an array with their

addresses.

# include <stdio.h>

# include <conio.h>

void main ()

{

clrecr () j

int b[4J«{2,4,3,7};

printf (m\nb[0] Value =%d Address=%u#r ,b [0] ,&b[0]);

printf (*\nb [1] Value »%d Address »%u",b[l] ,&b[l]);

printf ("\nb [2] Value «%d Address *%u",b[2] ,&b[2]);

pri^xtf ("\nb[3] Value »%d Address -%u",b[3] ,&b[3])/

>

o m r y ji

1>I0} Value => 2 Address: 4090

b(l] Value = 4 Address: 4092

b[2) Value-a 3 Address: 4094

b(3] Value o 7 Address: 4096

Explanation In the above program an array b[4 ] is declared and initialized. The cout statement

displays the array elements with their addresses. The b [ 0 ] refers to first element; b [ 1 ] refers to second

element and so on. Fig. 2.5 shows element numbers, elements and addresses.

Fig. 2.5 Array elements in memory