Use of Arrays
- Storing
more than one value at a time under a single name.
- Reading,
processing and displaying the array elements is far easier
ARRAYS
Arrays are variables that are capable
of having more than one value at a time. “An array is a collection of
homogenous elements of same data type stored in adjacent locations.” The same
data type could be all ints (or) floats (or) chars etc., An array is an
user-defined data type
Syntax: datatype array_name[size];
size is the maximum number of
elements that can be stored in the array.
Ex: int a[100]
Float
rates[5];
Char
name[20];
Arrays are of 3 types:-
- One Dimensional Array
- Two Dimensional Array
- Multi-Dimensional Array
Declaration
of 1-D Array
Ex: int a[10];
The above statement tells the
compiler to reserve sufficient amount of space to store 10 integers and specify
a name ‘a’ to the entire collection.
Initialization
of 1-D Array:
Like a variable an array can also be
initialized at the time of declaration.
int num[5]={1,2,3,4,5};
to access the number 3 we can simply
write a[2]
int digits[ ] =
{1,2,3,4,5,6,7,8,9,10};
char name[5]={‘e’,’i’,’o’,’u’,’a’};
float rate[3]={20.5,34.5,67.9};
//program
to accept and display the array
#include<stdio.h>
#include<conio.h>
void main()
{
int a[10],n,i;
printf("How many nos do u want
to enter:");
scanf("%d",&n); //size of the array
printf("Enter the
Numbers:");
for(i=0;i<n;i++)
scanf("%d",&a[i]); //reading elements into
the array
printf("The elements in the
array are...");
for(i=0;i<n;i++)
printf("%d\t",a[i]); //displaying the
elements in the array
getch();
}
Output:
How many nos do u want to enter:5
Enter the Numbers:1
2
3
4
5
The elements in the array
are...1 2 3
4 5
//Program
to read and display the array in reverse
#include<stdio.h>
#include<conio.h>
void main()
{
int a[10],n,i;
printf("How many nos do u want
to enter:");
scanf("%d",&n); //size of the array
printf("Enter the
Numbers:");
for(i=0;i<n;i++)
scanf("%d",&a[i]); //reading elements into
the array
printf("The elements in the
array are...");
for(i=n-1;i>=0;i--)
printf("%d\t",a[i]); //displaying the
elements in the array in reverse order
getch();
}
Output:
How many nos do u want to enter:5
Enter the Numbers:1
2
3
4
5
The elements in the array are...5 4
3 2 1
//Program
to find the sum of array elements
#include<stdio.h>
#include<conio.h>
void main()
{
int
a[10],sum=0,n,i;
clrscr();
printf("Enter
the size of array:");
scanf("%d",&n);
printf("\nEnter
the elements into the array:");
for(i=0;i<n;i++)
scanf("%d",&a[i]);
for(i=0;i<n;i++)
sum=sum+a[i];
printf("\nThe
sum of the array elements are...%d",sum);
getch();
}
Output:
Enter the size of array:5
Enter the elements into the array:1 2
3 4 5
The sum of the array elements
are...15
//Program for Bubble Sort
#include<stdio.h>
void main()
{
int
a[10],n,i,j,t;
clrscr();
printf("How
many numbers:");
scanf("%d",&n);
printf("Enter
the numbers :");
for(i=0;i<n;i++)
scanf("%d",&a[i]);
printf("The
sorted list ...");
for(i=0;i<n-1;i++) //for ‘n’ elements n-1
passes
{
for(j=0;j<n-1-i;j++) //and each time n-1-I comparisons
{
if(a[j]>a[j+1])
{
t=a[j];
a[j]=a[j+1];
a[j+1]=t;
}
}
}
for(i=0;i<n;i++)
printf("\n\t\t%d",a[i]);
getch();
}
Output:
How many numbers:5
Enter the numbers :9 0 2 1 7
The sorted list ... 0
1 2 7
9
Searching:
Searching is a technique which
searches for the given element in the array. Ex: Google Search Engine,
Searching for a file, etc are based on this concept. Searching’s are of two
types namely:
- Linear Search
- Binary Search
Linear
Search:
This technique searches for the
element sequentially i.e., it searches for the search element starting from the
first element in the array. If the search values do not match with the first
element in the array then the search element is compared with the second
element in the array. If the values still do not match then the required
element is compared with the third element in the list. This process continues,
until the required element is found or the end of the list is reached.
Ex: Searching for the file starting
with the letter ‘s’, searching for files having extensions like .doc,.xls etc.
//program
for linear search
#include<stdio.h>
void main()
{
int
a[10],n,i,search,flag=0;
clrscr();
printf("How
many numbers:");
scanf("%d",&n);
printf("\nEnter
the numbers :");
for(i=0;i<n;i++)
scanf("%d",&a[i]);
printf("\nEnter
the element to be searched:");
scanf("%d",&search); //reading search element
for(i=0;i<n;i++)
{
if(a[i]==search) // comparing search element to the
{ //element in the array list.
flag=1;
break; //if element is found make
flag=1
}
}
if(flag==1) //if flag=1 it
means element found
printf("\nElement
found at position %d",i+1);
else //i+!
is the element position
printf("\nElement
Not Found");
getch();
}
Output:
How many numbers: 5
Enter the numbers: 2 8 4 7 1
Enter the element to be searched: 4
Element found at position 3
Output 2:
How many numbers: 5
Enter the numbers: 2 8 4 7 1
Enter the element to be searched: 6
Element Not Found
Explanation:
Initially flag=0
Elements in the array:
1 8 9 4 5
a[0]
a[1] a[2] a[3]
a[4]
Assume Search element as 9
First compare 9 with a[0] i.e., 1
(not equal)
Next compare 9 with a[1] i.e., 8 (not equal)
Next compare 9 with a[2] i.e., 9 (equal)
Now assign flag=1 and break the loop
and check whether flag=1 or not if yes print the message “element found”.
Assume Search element as 6
First compare 6 with a[0] i.e., 1
(not equal)
Next compare 6 with a[1] i.e., 8 (not equal)
Next compare 6 with a[2] i.e., 9 (not equal)
Next compare 6 with a[3] i.e., 4 (not equal)
Next compare 6 with a[4] i.e., 5 (not equal)
Now it reaches to the end of the list
so the flag value will not change it remains 0 so it prints “element not found”
Binary
Search:
In this search, to search the element
first the list of elements should be in the sorted order. The searching is done by finding the middle
element in the array. If the middle element is equal to the search element the
procedure stops. Otherwise it splits the
list into 2 halves, if search element is greater than the middle element then
it search in the lower list, if the search element is less than the middle
element then it search in the upper list. This procedure repeats until the
search element is found.
For Ex: Searching for a word in a
dictionary comes under this concept. Suppose we want to search the meaning for
knowledge we directly move to the page containing k letter and then to the
letters kn and so on. The words will be in the sorted order in the dictionary.
So we can directly move to that page that containing the alphabet.
Ex-2:
Telephone Directory, etc
//Program
for Binary Search
#include<stdio.h>
#include<conio.h>
void main()
{
int
a[10],flag=0,i,n,top,mid,bottom,key;
clrscr();
printf("\nEnter size of the array:");
scanf("%d",&n);
printf("\nEnter elements into the array in sorted order:");
for(i=0;i<n;i++)
scanf("%d",&a[i]);
printf("\nEnter element to be searched:");
scanf("%d",&key);
top = 0;
bottom = n-1;
while(top
<= bottom && flag == 0)
{
mid =
(top + bottom) /2 ;
if(a[mid] == key)
flag = 1;
else
if(key>a[mid])
top = mid + 1;
else
bottom = mid - 1;
}
if(flag
== 1)
printf("\nSearch element %d found at position %d",key,mid+1);
else
printf("\nSearch element %d is not found.",key);
}
Output
Enter size of the array: 5
Enter elements into the array in sorted order:
10 20
30 40 50
Enter
element to be searched: 40
Search element 40 found at position 4
Now
search element is 10
top
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mid
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bottom
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2
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5
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6
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7
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8
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9
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10
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11
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0
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1
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2
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3
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4
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5
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6
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7
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Key=10
Top=0;bottom=n-1=7
Mid=top+bottom/2=0+7/2=3
A[3]=7
key>a[3] so, top=mid+1 i.e., it breaks the list into 2 now search will be in the bottom part of the list as key > mid element.
key>a[3] so, top=mid+1 i.e., it breaks the list into 2 now search will be in the bottom part of the list as key > mid element.
top
|
mid
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bottom
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2
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5
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6
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7
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8
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9
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10
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11
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0
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1
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2
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3
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4
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5
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6
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7
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Key=10
Top=4;bottom=n-1=7
Mid=top+bottom/2=4+7/2=5
A[5]=9
key>a[5] so, top=mid+1 i.e., it breaks the list again into 2 now search will be in the bottom part of the list as key > mid element.
key>a[5] so, top=mid+1 i.e., it breaks the list again into 2 now search will be in the bottom part of the list as key > mid element.
top
|
mid
|
bottom
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2
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5
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6
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7
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8
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9
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10
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11
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0
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1
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2
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3
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4
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5
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6
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7
|
Key=10
Top=5;bottom=n-1=7
Mid=top+bottom/2=5+7/2=6
A[6]=10 // a[mid]
is equal to key so search
found
Now search element is 12
Now search element is 12
top
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mid
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bottom
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2
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5
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6
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7
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8
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9
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10
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11
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0
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1
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2
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3
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4
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5
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6
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7
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Key=12
Top=0;bottom=n-1=7
Mid=top+bottom/2=0+7/2=3
A[3]=7
key>a[3] so, top=mid+1 i.e., it breaks the list into 2 now search will be in the bottom part of the list as key > mid element.
key>a[3] so, top=mid+1 i.e., it breaks the list into 2 now search will be in the bottom part of the list as key > mid element.
top
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A[mid]
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bottom
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2
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5
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6
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7
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8
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9
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10
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11
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0
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1
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2
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3
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4
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5
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6
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7
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Key=12
Top=4;bottom=n-1=7
Mid=top+bottom/2=4+7/2=5
A[5]=9
key>a[5] so, top=mid+1 i.e., it breaks the list again into 2 now search will be in the bottom part of the list as key > mid element.
key>a[5] so, top=mid+1 i.e., it breaks the list again into 2 now search will be in the bottom part of the list as key > mid element.
top
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A[mid]
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bottom
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2
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5
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6
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7
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8
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9
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10
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11
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0
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1
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2
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3
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4
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5
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6
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7
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Key=12
Top=5;bottom=n-1=7
Mid=top+bottom/2=5+7/2=6
A[6]=10
key>a[6] so, top=mid+1 i.e., it breaks the list again into 2 now search
will be in the bottom part of the list as key > mid element.
top
|
bottom
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||||||
2
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5
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6
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7
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8
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9
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10
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11
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0
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1
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2
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3
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4
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5
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6
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7
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Key=12
Top=6;bottom=n-1=7
Mid=top+bottom/2=6+7/2=6
A[6]=10
key>a[6] so, top=mid+1 i.e., it breaks the list again into 2 now search
will be in the bottom part of the list as key > mid element.
Top,bottom
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|||||||
2
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5
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6
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7
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8
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9
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10
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11
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0
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1
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2
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3
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4
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5
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6
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7
|
Key=12
Top=7;bottom=n-1=7
Mid=top+bottom/2=7+7/2=7
A[7]=11
key>a[6] so, top=mid+1 i.e., it breaks the list again into 2 now search
will be in the bottom part of the list as key > mid element.
Top,bottom
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|||||||
2
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5
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6
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7
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8
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9
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10
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11
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0
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1
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2
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3
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4
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5
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6
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7
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Key=12
Top=8;bottom=n-1=7 as top>bottom
it stops searching and prints element not found
Two-Dimensional
Array
A 2-D array is nothing but a
collection of 1-D Array. 2-D arrays are mainly used when values are to be
stored in the table form or to represent in rows and columns format. 2-D arrays
are used to represent any data in table or rows and columns format.
Declaration
of 2-D Array
Syntax: type arrayname[row size][col size];
int m[5][4];
Here m is an array variable which has
5 rows and 4 columns. Here 40 bytes (20 integers) gets allocated to ‘m’.
//Program for reading & printing
a 2-D array
#include<stdio.h>
#include<conio.h>
void main()
{
int a[10][10],m,n,i,j;
printf("Enter the size of matrix:");
scanf("%d%d",&m,&n);
printf("\nEnter the elements into
array:");
for(i=0;i<m;i++)
for(j=0;j<n;j++)
scanf("%d",&a[i][j]);
printf("\nElements in the array
are:\n");
for(i=0;i<m;i++)
{
for(j=0;j<n;j++)
{
printf("%3d",a[i][j]);
}
printf("\n");
}
getch();
}
Output
Enter the size of matrix:2 2
Enter the elements into array:1 2 3 4
Elements in the array are:
1 2
3 4
//sum of 2 matrices
#include<stdio.h>
#include<conio.h>
void main()
{
int
a[5][5],b[5][5],c[5][5],i,j,m,n,p,q;
clrscr();
printf("Enter
the size of matrix A:");
scanf("%d%d",&m,&n);
printf("\nEnter
the elements into matrix A:");
for(i=0;i<m;i++)
for(j=0;j<n;j++)
scanf("%d",&a[i][j]);
printf("\nEnter
the size of matrix B:");
scanf("%d%d",&p,&q);
printf("\nEnter
the elements into matrix B:");
for(i=0;i<p;i++)
for(j=0;j<q;j++)
scanf("%d",&b[i][j]);
if((m!=p)
&& (n!=q))
printf("\nMatrix
Addition is not possible");
else
{
for(i=0;i<m;i++)
{
for(j=0;j<n;j++)
{
c[i][j]=a[i][j]+b[i][j];
}
}
printf("\nAddition
of 2 matrices are...\n");
for(i=0;i<m;i++)
{
for(j=0;j<n;j++)
{
printf("%3d",c[i][j]);
}
printf("\n");
}
}
getch();
}
Output:
Enter the
size of matrix A: 3 3
Enter elements into matrix-A:
1 2 3 4 5 6 7 8 9
Enter the
size of matrix B: 3 3
Enter elements into matrix-B:
1 2 3 4 5 6 7 8 9
Addition of 2 matrices are...
2 4
6
8 10 12
14 16 18
//multiplication of 2 matrices
#include<stdio.h>
#include<conio.h>
void main()
{
int
a[5][5],b[5][5],c[5][5],k,i,j,m,n,p,q;
clrscr();
printf("Enter
the size of matrix A:");
scanf("%d%d",&m,&n);
printf("\nEnter
the elements into matrix A:");
for(i=0;i<m;i++)
for(j=0;j<n;j++)
scanf("%d",&a[i][j]);
printf("\nEnter
the size of matrix B:");
scanf("%d%d",&p,&q);
printf("\nEnter
the elements into matrix B:");
for(i=0;i<p;i++)
for(j=0;j<q;j++)
scanf("%d",&b[i][j]);
if((m!=q)
&& (n!=p))
printf("\nMatrix
Multiplication is not possible");
else
{
for(i=0;i<m;i++)
{
c[i][j]=0;
for(j=0;j<p;j++)
{
for(k=0;k<n;k++)
{
c[i][j]=c[i][j]+(a[i][k]*b[k][j]);
}
}
}
printf("\nMultiplication
of 2 matrices are...\n");
for(i=0;i<m;i++)
{
for(j=0;j<n;j++)
{
printf("%3d",c[i][j]);
}
printf("\n");
}
}
getch();
}
Output
Enter the
size of matrix A: 3 3
Enter elements into matrix-A:
1 2 3 4 5 6 7 8 9
Enter the
size of matrix B: 3 3
Enter elements into matrix-B:
1 2 3 4 5 6 7 8 9
Multiplication of 2 matrices are...
30 36 42
66 81 96
102 126 150
//transpose matrix
#include<stdio.h>
#include<conio.h>
void main()
{
int
a[5][5],b[5][5],i,j,m,n,p,q;
clrscr();
printf("Enter
the size of matrix A:");
scanf("%d%d",&m,&n);
printf("\nEnter
the elements into matrix A:");
for(i=0;i<m;i++)
for(j=0;j<n;j++)
scanf("%d",&a[i][j]);
printf("\nOriginal
Matrix is...\n");
for(i=0;i<m;i++)
{
for(j=0;j<n;j++)
{
printf("%3d",a[i][j]);
}
printf("\n");
}
printf("\nTranspose
of matrices is...\n");
for(i=0;i<m;i++)
{
for(j=0;j<n;j++)
{
b[i][j]=a[j][i];
printf("%3d",b[i][j]);
}
printf("\n");
}
getch();
}
Output:
Enter the size of matrix A: 4 3
Enter the elements into matrix A: 1 2 3 4 5 6 7 8 9 10 11 12
Original Matrix is:
1
2
3
4 5 6
7 8 9
10 11 12
Transpose of matrices is:
1 4
7 10
2 5
8 11
3 6
9 12
Multi-Dimensional Array:
Multi-dimensional arrays are widely
used in scientific computing. A 3-D array is a combination of 2-D array.
Ex: int x[2][4][5]
It is considered as 3-D array in
which there exist two 2-d arrays of size 4 rows and 5 columns.
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Initialization of 3-D array:
int a[2][4][5] :
{{{1,2},{1,4}},{{3,4},{4,5}}};
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//reading and printing 3-d array:
#include<stdio.h>
void main()
{
int a[2][4][5],i,j,m,k,n,p;
clrscr();
printf("enter the no of
planes,its rows and coloumns:");
scanf("%d%d%d",&p,&m,&n);
printf("\nenter the elements
into array:"); /*reading the array*/
for(k=0;k<p;k++)
{
for(i=0;i<m;i++)
{
for(j=0;j<n;j++)
{
printf("\nEnter
next value");
scanf("%d",&a[k][i][j]);
}
}
}
/* printing the data */
for(k=0;k<p;k++)
{
for(i=0;i<m;i++)
{
for(j=0;j<n;j++)
{
printf("%d\t",a[k][i][j]);
}
printf("\n");
}
}
getch();
}
Output:
enter the no of planes,its rows and
coloumns:2 2 2
enter the elements into array:
Enter next value1
Enter next value2
Enter next value3
Enter next value4
Enter next value1
Enter next value2
Enter next value3
Enter next value4
1 2
3 4
1 2
3 4
