Session 4

ARRAY in C
• Array is a collection or group of similar data type
elements stored in contiguous memory.

• The individual data items can be characters, integers,
floating points numbers and so on .

• Here contiguous memory allocation means array
occupies contiguous bytes as needed in the memory.

Declaring single dimension Arrays
• We can declare an array by specify its data
type, name and the number of elements the
array holds between square brackets
immediately following the array name.

• Here is the syntax:
data_type array_name[size];

Declaring single dimension Array
• For example, to declare an integer array which
contains 10 elements we can do as follows:

int values[10];

Accessing Single Dimension Array
• We can access array elements via
indexes array_name[index]. Indexes of array
starts from 0
• With each subscript enclosed in square
brackets.

• For example,
values[0]=5;
values[1]=10;
printf(“%d”,values[1]);

Initializing Arrays
• It is like a variable, an array can be initialized.

• To initialize an array, you provide initializing
values which are enclosed within curly braces
in the declaration and placed following an
equals sign after the array name.

• Here is an example of initializing an integer
array.
int list[5] = {2,1,3,7,8};

Multi dimensional Arrays:
• Often there is a need to store and manipulate
two dimensional data structure such as matrices
& tables.

• Here the array has two subscripts. One subscript
denotes the row & the other the column.

• The declaration of two dimension arrays is as
follows:
data_type array_name[row_size][column_size];
int m[10][20];

Declaring Multi Dimensional Array
float table [50][50];
char page[50][50];

int num[3][3];
0 1 2
0
1
2

Accessing two dimensional arrays
int values[2][2];
values[0][0]=1; values[0][1]=2;
values[1][0]=3; values[1][1]=4;

int num[2][2]={1,2,3,4};
int matrix[3][3]
={{11,12,13}, {21,22,23}, {32,31,33}};

ARRAY AND STRINGS
• The gets and puts functions:

• The gets and puts functions facilitate the transfer
of strings between the computer and the
standard input/output devices.

• Each of these functions accepts a single
argument. The argument must be a data item
that represents a string(e.g. character array).

Example of using gets and puts
#include<stdio.h>
void main()
{
char inne[80];
gets(line);
puts(line);
}
The gets and puts functions offer simple
alternatives to the use of scanf and printf for
reading and displaying strings

String library functions
• strlen()
• This function counts a number of characters
present in a string while giving a call to the
function.
char msg[] = “Lord krishna”;
int n;
n=strlen(msg);
printf(“length of string =%d”, n);

• strcpy()
• This function copies the contents of one string
to another.
• The base address of source and target strings
are supplied to the function.

char source[] = “Lord Krishna”;
char target[15];
strcpy(target, source);
printf(“Source string is : %s”, source);
printf(“target string is :%s”,target);

• strcat()
• This function concatenates the source string
at the end of target sting.
char s[] = “Lord”;
char t[] = “Krishna”;
strcat(t,s);
printf(“source string is %sn”, s);
printf(“target stirng is %sn”, t);

• strcmp()
• This function compares two strings and
returns some integer value.
• If both the strings are equal then it returns 0
otherwise it returns some other integer value.
void main()
{
char s1[]=”Jerry”; char s2[]=”Ferry”;
int j= strcmp(s1, s2);
printf(“%d”, j);

Understanding Functions
• What is Function?
• A function in C language is a block of code that
performs a specific task.

• It is reusable i.e. it can be executed from as
many different parts in a C Program as
required.

• It also optionally returns a value to the calling
program

Structure of a Function
<return type> FunctionName (Argument1,
Argument2, Argument3……)
{
Statement1;
Statement2;
}
int sum (int x, int y)
{
int result;
result = x + y;
return (result);
}

Types of functions:
A function may belong to any one of the
following categories:

• Functions with no arguments and no return
values.
• Functions with arguments and no return values.
• Functions with arguments and return values.
• Functions that return multiple values.
• Functions with no arguments and return values.

Advantages of using functions:
• It makes possible top down modular
programming.

• The length of the source program can be
reduced.

• It becomes uncomplicated to locate and
separate a faulty function for further study.

• c programmer can use function written by
others, instead of starting over from scratch.

Function Example
#include <stdio.h>
void printMessage ()
{
printf ("Programming is fun.n");
}
void main ()
{
printMessage ();
}

Function Which Return Values
#include <stdio.h>
int add (int x,int y)
{
int result; result=x+y;
return(result);
}
void main ()
{
int total;
total=add(10,12);

Recursive Function
• Recursive function is a function which
contains a call to itself.

• Recursive function allows you to divide your
complex problem into identical single simple
cases which can handle easily.

• This is also a well-known computer
programming technique: divide and conquer.

Example of recursive function
# include<stdio.h>
int factorial(int number)
{
if(number <= 1)
return 1;
return number * factorial(number - 1);
}
void main()
{
int x = 5;
printf("factorial of %d is %d",x,factorial(x));
}

Scope Rule of Functions
void main( )
{
int i = 20 ;
display ( i ) ;
}
void display ( int j )
{
int k = 35 ;
printf ( "n%d", j ) ;
printf ( "n%d", k ) ;
}

Session 4

More Related Content

What's hot (20)

Similar to Session 4 (20)

Recently uploaded (20)

Session 4