Nested while loop
Note:
Before beginning with this lesson you should see the previous lessons of C Programming Language Tutorial VII. This
is helping you to understand the concept of nested loop.
Nested
Loop:
In case of nested loop, you have more than
one loop. The structure of nested loop is loop within loop. If for loop is
within while loop or for loop within for loop or while loop within for loop and
vice versa known as nested loop.
In this case first outer condition is
evaluated and then first inner loop gets execute till the inner condition is
true. After termination of inner loop, outer loop gets executed and inner loop
get reset this whole cycle is going on till the outer condition is true. Let us
clear this concept by following syntax:
Nested
while loop
while(outer condition)
{
while(inner condition)
{
-------
-------
-------
}
}
While
creating program of nested loop you must be think of each and every step.
e.g.
– what is outer condition?
What is inner condition?
How to reset inner loop?
Let
us see in details, generally outer condition is useful only to jump value step
by step. i.e. if num=1 then it will 2,3,4……. till given range. Use inner
condition same as you had used in case of while loop. Reset loop means to set
any variable of inner loop at previous initialized value.
You
have to study following program to grip concept of working of nested loop –
|
//nested
while loop
#include<stdio.h>
#include<conio.h>
void
main()
{
int i=1,j=1; //declaration
and initialization of variables
clrscr();
while(i<=5) //outer
condition
{
while(j<=3) //inner
condition
{
printf("\ni = %d \t j = %d",i,j); //simply
print value of i and j
j++; //increment
to j for getting termination of inner loop
}
printf("\n------------------------------------");
j = 1; //reset
inner loop
i++; // increment
to i for getting termination of outer loop
}
getch();
}
|
|
o/p:
i
= 1 j = 1
i
= 1 j = 2
i = 1 j = 3
i
= 2 j = 1
i
= 2 j = 2
i = 2 j = 3
i
= 3 j = 1
i
= 3 j = 2
i = 3
j = 3
i
= 4 j = 1
i
= 4 j = 2
i = 4 j = 3
i
= 5 j = 1
i
= 5 j = 2
i = 5 j = 3
|
You
have created program to print multiplication table of given number. But if you
have a set or range of numbers and want to print multiplication table of each
value then you can simply apply nested loop.
Let
us see:
|
//multiplication
table
#include<stdio.h>
#include<conio.h>
void
main()
{
int num=1,cnt=1,ans,range;
clrscr();
printf("\nEnter any range for table:
");
scanf("%d",&range);
while(num<=range) //outer loop is
used to jump one by one number till range
{
printf("\nMultiplication Table of %d : \n",num);
//you can find that inner loop is same as you have used while
printing multiplication table of single number
while(cnt<=10)
{
ans = num * cnt; //process
printf("\n%d * %-2d =
%d",num,cnt,ans); //It will print following mentioned output
cnt++;
}
cnt=1;
//after printing table for one time you
must need to reset counter for next set of numbers
num++; //it
will give you next number
}
getch();
}
|
|
o/p:
Enter
any range for table: 3
Multiplication
Table of 1 :
1
* 1 = 1
1
* 2 = 2
1
* 3 = 3
1
* 4 = 4
1
* 5 = 5
1
* 6 = 6
1
* 7 = 7
1
* 8 = 8
1
* 9 = 9
1
* 10 = 10
Multiplication
Table of 2 :
2
* 1 = 2
2
* 2 = 4
2
* 3 = 6
2
* 4 = 8
2
* 5 = 10
2
* 6 = 12
2
* 7 = 14
2
* 8 = 16
2
* 9 = 18
2
* 10 = 20
Multiplication
Table of 3 :
3
* 1 = 3
3
* 2 = 6
3
* 3 = 9
3
* 4 = 12
3
* 5 = 15
3
* 6 = 18
3
* 7 = 21
3
* 8 = 24
3
* 9 = 27
3
* 10 = 30
|
Assignment:
From above program you can be modify program of factorial by using range and
print sum of all factorial.
In
previous lesson you know that how to check whether given number is palindrome
or not palindrome. Now you can apply range to find all palindrome numbers from
given range.
Let
us see the program –
|
//program
to print all palindrome numbers from given range
#include<stdio.h>
#include<conio.h>
void
main()
{
int no=100,rem,rev=0,temp,range; //number
starts from zero
clrscr();
printf("\nEnter any range: ");
scanf("%d",&range); //range
must be greater than 100
while(no<=range) //number
goes from 100 till given range
{
temp=no;
//assigns value
of number to temp
while(temp>0) //temp is used
here because you will need current value of number in outer loop
{
rem = temp % 10;
temp = temp / 10;
rev = rem + rev * 10;
}
if(no == rev) //check
whether the value of no is equal to rev
printf("\nPalindrome number = %d",no);
rev=0; //for each
number rev=0 again
no++; //increment to
get next number
}
getch();
}
|
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o/p:
Enter
any range: 200
Palindrome
number = 101
Palindrome
number = 111
Palindrome
number = 121
Palindrome
number = 131
Palindrome
number = 141
Palindrome
number = 151
Palindrome
number = 161
Palindrome
number = 171
Palindrome
number = 181
Palindrome
number = 191
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Assignment : Create a program to print all prime numbers by setting start range and end range.
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