Unit 3 arrays and_string

Array
 An Array is a collection of similar data items, that
are stored under a common name.
 Array might belonging to any of the data types
 Array size must be a constant value.
 Always, Contiguous(adjacent) memory locations
are used to store array elements in memory.
KIRTHIKA KM /AP/CSE

Uses of array
 Stores the elements of same data type.
 Used for maintaining multiple variable names
using a single name.
 Used for sorting elements.
 Matrix operations can be performed using arrays.
 Arrays are also used in CPU scheduling.
KIRTHIKA KM /AP/CSE

Types of arrays
 Types
 One-Dimensional array
 Two-Dimensional array
 Multi-Dimensional array
KIRTHIKA KM /AP/CSE

One-Dimensional array
 Array declaration:
 Syntax:
data_type array_name[size];
 Example: int x[3];
X[0]
X[1]
X[2]
x
KIRTHIKA KM /AP/CSE

Array initialization
 The initializer for an array is a comma-separated list of constant
expressions enclosed in braces ({ }).
 The initializer is preceded by an equal sign (=).
 It is not necessary to initialize all elements in an array. If an array
is partially initialized, elements that are not initialized receive
the value of the appropriate type.
 Array initialization can be made either :
 At compile time or
 At run time
KIRTHIKA KM /AP/CSE

At compile time
 Syntax:
data_type array_name[size]={variables};
Example: int x[3]={5,3,7};
5
3
7
X[0]
X[1]
X[2]
x
KIRTHIKA KM /AP/CSE

At Run time
 Array can also be initialized at the run time.
Example:
while(i<10)
{
if(i<5)
sum[i]=0;
else
sum[i]=sum[i]+i;
}
Example:
scanf(“%d%d”,&a[0],&a[1]);
KIRTHIKA KM /AP/CSE

Example
#include<stdio.h>
#include<conio.h>
void main()
{
int x[2],i;
printf("nEnter the inputs:");
for(i=0;i<2;i++)
scanf("%d",&x[i]);
for(i=0;i<2;i++)
printf("nThe value in x[%d] is %d",i,x[i]);
getch();
}
KIRTHIKA KM /AP/CSE

Output
Enter the inputs:3
6
The value in x[0] is 3
The value in x[1] is 6
KIRTHIKA KM /AP/CSE

Example
#include<stdio.h>
#include<conio.h>
void main()
{
int i;
char x[5]={'a','b','c','d','e'};
clrscr();
for(i=0;i<5;i++)
printf("nThe value in x[%d] is %c",i,x[i]);
getch();
}
KIRTHIKA KM /AP/CSE

Output
The value in x[0] is a
The value in x[1] is b
The value in x[2] is c
The value in x[3] is d
The value in x[4] is e
KIRTHIKA KM /AP/CSE

Two-Dimensional array
 Array declaration
 Syntax:
data_type array_name[row_size] [col_size];
 Example: int x[3][2];
X[0][0]
X[1][0]
X[2][0]
Col 0 Col 1
row 0
row 1
row 2
X[0][1]
X[1][1]
X[2][1]
KIRTHIKA KM /AP/CSE

2-D Array Initialization
 Syntax:
data_type array_name[row_size] [col_size];={variables};
 Example: int x[2][2]={1,50,2,75};
KIRTHIKA KM /AP/CSE

Example
 int x[2][2]={ {1,50},
{2,75}
};
(or)
 int x[ ][2]={ {1,50},
{2,75}
};
KIRTHIKA KM /AP/CSE

 The array elements will be stored in contiguous
memory locations, and it is illustrated below:
1 50
2 75
row 0
row 1
Col 0 Col 1
KIRTHIKA KM /AP/CSE

Example
#include<stdio.h>
#include<conio.h>
void main()
{
int i,j;
int x[2][2]={ {1,50},
{2,75}
};
clrscr();
for(i=0;i<2;i++)
for(j=0;j<2;j++)
printf("nThe value in x[%d][%d] is %d",i,j,x[i][j]);
getch();
}
KIRTHIKA KM /AP/CSE

Output
The value in x[0][0] is 1
KIRTHIKA KM /AP/CSE

Example
#include<stdio.h>
#include<conio.h>
void main()
{
int i,j;
int x[][2]={ {1,50},{2,75},{3,65}};
clrscr();
for(i=0;i<=2;i++)
for(j=0;j<2;j++)
printf("nThe value in x[%d][%d] is %d",i,j,x[i][j]);
getch();
}
KIRTHIKA KM /AP/CSE

Output
KIRTHIKA KM /AP/CSE

Matrix Addition
#include<stdio.h>
#include<conio.h>
void main()
{
int i,j,k,r1,r2,c1,c2;
int a[5][5],b[5][5],c[5][5];
clrscr();
step1:
printf("n Enter the size of matrix A:");
scanf("%d%d",&r1,&c1);
printf("n Enter the size of matrix B: ");
if((c1==c2)&&(r1==r2))
goto step2;
else
goto step1;
KIRTHIKA KM /AP/CSE

step2:
printf("n Enter the elements of matrix A n");
for(i=0;i<r1;i++)
{
for(j=0;j<c1;j++)
{
scanf("%d",&a[i][j]);
}
}
printf("n Enter the elements of matrix B n");
for(i=0;i<r2;i++)
{
for(j=0;j<c2;j++)
{
scanf("t%d",&b[i][j]);
}
}
KIRTHIKA KM /AP/CSE

for(i=0;i<r1;i++)
{
for(j=0;j<c1;j++)
{
c[i][j]=0;
c[i][j]=c[i][j]+a[i][j]+b[i][j];
}
}
printf("n The resultant matrix after addition of A & B isn");
for(i=0;i<r1;i++)
{
for(j=0;j<c1;j++)
printf("%dt",c[i][j]);
printf("n");
}
getch();
}
KIRTHIKA KM /AP/CSE

Output
Enter the size of matrix A: 2
2
Enter the size of matrix B: 2
2
Enter the elements of matrix A
2
2
2
2
Enter the elements of matrix B
3
3
3
3
The resultant matrix after addition of A&B is
5 5
5 5
KIRTHIKA KM /AP/CSE

Matrix Multiplication
#include<stdio.h>
#include<conio.h>
void main()
{
int i,j,k,r1,r2,c1,c2;
int a[5][5],b[5][5],c[5][5];
clrscr();
step1:
printf("n Enter the size of matrix A n");
printf("n Enter the size of matrix B n");
if(c1==r2)
goto step2;
else
goto step1;
KIRTHIKA KM /AP/CSE

for(i=0;i<r1;i++)
{
for(j=0;j<c2;j++)
{
c[i][j]=0;
for(k=0;k<c1;k++)
{
c[i][j]=c[i][j]+a[i][k]*b[k][j];
}
}
}
for(i=0;i<r1;i++)
{
for(j=0;j<c2;j++)
printf("%dt",c[i][j]);
printf("n");
}
getch();
} KIRTHIKA KM /AP/CSE

Output
Enter the size of matrix A:2
2
Enter the size of matrix B:2
2
4
4
4
4
4
4
4
4
The resultant matrix is
32 32
32 32 KIRTHIKA KM /AP/CSE

Enter the size of matrix A:2
3
Enter the size of matrix B:3
2
1
2
3
4
5
6
2
4
6
8
2
4
The resultant matrix is
20 32
50 80
KIRTHIKA KM /AP/CSE

Passing array to Function
 An array can be passed as a parameter to a function by
specifying the array's name without an index.
 Here an array is transferred as parameter to a function.
void main() void fun(n,b[])
{ {
void fun(int,int); int x,b[5];
int a[5],n; …………..
…………… …………..
fun(n,a);
…………… }
}
KIRTHIKA KM /AP/CSE

Example
#include<stdio.h>
#include<conio.h>
void add(int,int b[]);
void main()
{
int a[5],i,n;
clrscr();
printf("n Enter the Number: ");
scanf("%d",&n);
printf("n Enter the Values: ");
for(i=0;i<n;i++)
scanf("%d",&a[i]);
add(n,a);
}
KIRTHIKA KM /AP/CSE

void add(int x,int b[])
{
int sum=0,i;
for(i=0;i<x;i++)
sum=sum+b[i];
printf("nThe sum is: %d",sum);
}
KIRTHIKA KM /AP/CSE

Output
Enter the Number: 5
Enter the Values: 1
2
3
4
5
The sum is: 15
KIRTHIKA KM /AP/CSE

Array of Characters
 In an array the characters are terminated by the null
(‘0’) character.
 Example: char a[]={a,b,c};
a b c 0
KIRTHIKA KM /AP/CSE

Example
#include<stdio.h>
#include<conio.h>
void main()
{
int i=0;
char a[]="abcd";
clrscr();
while(a[i]!='0')
{
printf("t%c",a[i]);
i++;
}
}
KIRTHIKA KM /AP/CSE

Output
a b c d
KIRTHIKA KM /AP/CSE

Multi Dimensional Array
 Arrays can have more than one dimension, these arrays-of-
arrays are called multidimensional arrays.
 Here is the general form of a multidimensional array
declaration:
datatype array_name [size1][size2]….[size n]
datatype - type of the data.
array_name -name of the array.
size -size of the array.
KIRTHIKA KM /AP/CSE

 They are very similar to standard arrays with the
exception that they have multiple sets of square
brackets after the array identifier.
 A two dimensional array can be thought of as a grid of
rows and columns.
 A two-dimensional array is an example in this section,
although the techniques can be extended to three or
more dimensions.
 The simplest form of the multidimensional array is the
two-dimensional array.
KIRTHIKA KM /AP/CSE

Example:
int a[3][3][3];
Col 0 Col 1 Col 2
row 0
row 1
row 2
X[0][0]
X[1][0]
X[2][0]
X[0][1]
X[1][1]
X[2][1]
X[0][2]
X[1][2]
X[2][2]
KIRTHIKA KM /AP/CSE

String
 The string is actually a one-dimensional array of characters
which is terminated by a null character '0'.
 All the string handling functions are prototyped in: string.h
header file. So while using any string related function, don't
forget to include string.h.
 String constants have double quote marks around them.
 String constants can be assigned to a char array either with no
size specified, or the size can also be specified, but don't forget to
leave a space for the null character.
KIRTHIKA KM /AP/CSE

String Handling Functions
 Strings are often needed to be manipulated by the programmer
according to the need of a problem. Hence, C provides a variety of
string handling functions.
 String handling functions refers to a group of functions
implementing various operations on strings.
 Some of the operations performed by the string handling
functions includes:
 Length (number of characters in the string).
 Concatenation (adding two are more strings)
 Comparing two strings.
 Substring (Extract substring from a given string)
 Copy(copies one string over another)
KIRTHIKA KM /AP/CSE

 The various string handling functions supported by C are as
follows:
 strlen()
It is used to find the length of the string.
syntax:
strlen(string)
 strcpy()
It is used to copy one string to another.
syntax:
strcpy(string1,string2)
 strcat()
It is used to combine two strings.
syntax:
strcat(string1,string2)
KIRTHIKA KM /AP/CSE

 strcmp()
It is used to compare two strings.
syntax:
strcmp(string1,string2)
 Returns 0 if two strings are equal.
 Return value <0 if s1 is less than s2.
 Return value >0 if s1 is greater than s2.
 strrev()
It used to reverse a string.
syntax:
strrev(string)
 strlwr(), strupr()
It used to change the case of a string.
syntax:
strlwr(string)
strupr(string)
KIRTHIKA KM /AP/CSE

 strncpy()
It used to copy ‘n’ characters of one string to another.
 strstr()
It is used to determine the first occurrence of a given string
in another string.
 strncat()
It appends source string to destination string up to specified
length.
 strspn()
It is used to find up to what length two strings are identical.
KIRTHIKA KM /AP/CSE

 strncmp()
It is used to compare ‘n’ character of two strings.
 strcmpi()
It is used to compare two strings without regarding the case.
 strnicmp()
It is used to compare first ‘n’ characters of two strings without
regarding the case.
 strchr()
It is used to determine the first occurrence of a given character
in a string.
 strrchr()
It is used to determine the last occurrence of a given character
in a string.
KIRTHIKA KM /AP/CSE

Example 1
#include<stdio.h>
#include<conio.h>
#include<string.h>
void main()
{
char a[]="college";
int b;
clrscr();
b=strlen(a);
printf("nThe length of the string is %d",b);
getch();
}
Output:
The length of the string is 7
KIRTHIKA KM /AP/CSE

Example 2
#include<stdio.h>
#include<conio.h>
#include<string.h>
void main()
{
char a[ ]="IT";
char b[ ]="Dept";
clrscr();
strcpy(a,b);
printf("nThe string is %s",a);
getch();
}
Output:
The string is Dept
KIRTHIKA KM /AP/CSE

Example 3
#include<stdio.h>
#include<conio.h>
#include<string.h>
void main()
{
char a[ ]="IT";
char b[ ]="Dept";
clrscr();
strcat(a,b);
printf("nThe string is %s",a);
getch();
}
Output:
The string is ITDept
KIRTHIKA KM /AP/CSE

Example 4
#include<stdio.h>
#include<conio.h>
#include<string.h>
void main()
{
char a[ ]="itdept";
char b[ ]="it";
int i;
clrscr();
i=strcmp(a,b);
if(i==0)
printf("nstrings are equal:%d",i);
else if(i<0)
printf("nstring1 is less than string2:%d",i);
KIRTHIKA KM /AP/CSE

else
printf("nstring1 is greater than string2:%d",i);
getch();
}
Output:
string1 is greater than string2:100
KIRTHIKA KM /AP/CSE

Example 5
#include<stdio.h>
#include<conio.h>
#include<string.h>
void main()
{
char a[ ]="itdept";
clrscr();
printf("nThe string is :%s",a);
strupr(a);
printf("nThe string after conversion to uppercase :%s",a);
strlwr(a);
printf("nThe string after conversion to lowercase :%s",a);
getch();
}
KIRTHIKA KM /AP/CSE

Output
The string is : itdept
The string after conversion to uppercase :ITDEPT
The string after conversion to lowercase : itdept
KIRTHIKA KM /AP/CSE

Example 6
#include<stdio.h>
#include<conio.h>
#include<string.h>
void main()
{
char a[ ]="Dept";
clrscr();
printf("nThe string is %s",strrev(a));
getch();
}
Output:
The string is tpeD
KIRTHIKA KM /AP/CSE

Example 7
#include<stdio.h>
#include<conio.h>
#include<string.h>
void main()
{
char a[ ]="itdept";
char b[15];
int i=0;
clrscr();
strncpy(b,a,2);
b[2]='0';
printf("nThe string is :%s",b);
getch();
}
Output:
The string is :it KIRTHIKA KM /AP/CSE

String Palindrome
#include<stdio.h>
#include<conio.h>
#include<string.h>
void main()
{
int len,i,j;
char str[15];
clrscr();
printf("n Enter the string:");
scanf("%s",str);
len=strlen(str);
KIRTHIKA KM /AP/CSE

for(i=0,j=len-1;i<len/2;i++,j--)
{
if(str[i]!=str[j])
{
printf("n The String is not a palindrome");
getch();
exit(0);
}
}
printf("n The String is a palindrome");
getch();
}
Output:
Enter the string: abcba
The String is a palindrome
KIRTHIKA KM /AP/CSE

Unit 3 arrays and_string

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