Array in C++
Array
Array is a collection of similar type of data that shares a
common name.
In C++, all arrays consist of contiguous memory location.
To find the size of array-
Array (size/length) =U-L+1
where U=upper value ,L=lower value
Ex.
If the array element numbered as -7,-6,-5…….. 0, 1, 2………. 15,
then find the length.
Array size=15-(-7) +1
=15+7+1
=23
Address calculation
Address of element with subscript I= Base address +ES (I-L)
Where ES is size of an array element L is lower bound of
array.
Q. what will be the address of 5th element in a
floating -point array implemented in C++? The array is specified as Amount
[16]. The base address of array is 1058.
Sol. Address of amount [4] =base add +ES(I-L)
L=0
ES=4
Base
address=1058
=1058+ 4(4-0)
=1058+16
=1074
Basic operations on One-dimensional Array
Searching
° Linear search
In a linear search each element of array is compared with
the given item to be searched for, one by one.
Algorithm
/*Initialize counter by assigning lower bound value of an
array.*/
Step1 Set ctr=L
Step2 Repeat stem. 3 through 4 until ctr>U
Step3 If Ar(ctr)==ITEM then
{ print “search successful”
print ctr,”is the location of”, ITEM
break
}
Step4
ctr=ctr+1
Step5
If ctr>U then
print “search unsuccessful!”
Step6
END.
°
Binary Search
This is very popular searching, you minimum possible
comparisons. For this searching array should be in ascending or descending
order.
For
Array AR[L,U] is stored in ascending order
1.
Set beg=L , last=U
2.
Repeat step 3 through 6 UNTIL beg>last
3.
mid=INT(beg+last)/2 //int is used to extract the
used to
extract the integer
part
4.
if AR[mid]==ITEM then
{
print “search successful”
print ITEM “found at”, mid
break
}
5.
If AR[mid]<ITEM then
beg=mid+1
6.
IF AR[mid]>ITEM
last
=mid-1
7.
If beg=last
print
“unsuccessful search”
8.
END
Sorting
°
Selection
°
Bubble
°
Insertion
2D-Array
Implementation of 2D Array in
memory
Address calculation
Row majored
Address of [I,J]
element=B+W[c(I-Lr)+(J-Lc)]
Where B=base address ,W=element
size, Lr=first row number, Lc=first column number
Ex. A 2-D array defined as
A[4…7,-1……3] required 2 words of storage for each element. If array is stored
in row major, calculate the address of A[6,2],base address is 100.
Sol. Address [I, J]
=B+W[c(I-Lr)+(J-Lc)]
B=100, W=2
Lr=4, Lc=-1
c= 3+1+1=5
A[6,2]=100+2[5(6-4)+(2-(-1))]
=100+2[5x2
+3]
=100 +26
=126
Column majored
Address of[I,J]
element=B+W[(I-Lr)+r(J-Lc)]
Where r=no of rows
Operation in 2-D array
#include<iostream.h>
#include<process.h>
void main()
{
int a[10][10], b[10][10], c[10][10];
int i, j, m, n, p, q;
cout<<”Input the rows and
columns of matrix a”;
cin>>m>>n;
cout<<”Input the rows and
columns of matrix b”;
cin>>p>>q;
if(m==p)&&(n==q)
cout<<”Matrix can be added\n”;
else
{
cout<<”Matrix can’t be added\n”;
exit(0);
}
cout<<”\n Input matrix
A”;
for(i=0;i<m; i++)
{
for(j=0;j<n;j++)\
cin>>a[i][j];
}
cout<<”\n Enter matrix
B”;
for(i=0;i<p;i++)
{
for(j=0;j<q;j++)
cin>>b[i][j];
}
for (i=0;i<m;i++)
{
for (j=0;j<n;j++)
c[i][j]=a[i][j]+b[i][j];
}
cout<<”\n The sum is”;
for(i=0;i<m;i++)
{
cout<<”\n”;
for(j=0;j<n;j++)
cout<<” “<<c[i][j];
}
}
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