While Loop in Perl
In this tutorial, we will learn about while loop in Perl. We will cover the basics of iterative execution using while loops.
What is a While Loop
A while loop is a control flow statement that allows code to be executed repeatedly based on a given Boolean condition. The loop runs as long as the condition evaluates to true.
Syntax
The syntax for the while loop in Perl is:
while (condition) {
# Code block to be executed
}
The while loop evaluates the condition before executing the loop's body. If the condition is true, the code block inside the loop is executed. This process repeats until the condition becomes false.
Example 1: Printing Numbers from 1 to 5
- Declare a variable
$i
and initialize it to 1. - Use a while loop to print numbers from 1 to 5.
Perl Program
my $i = 1;
while ($i <= 5) {
print "$i\n";
$i++;
}
Output
1 2 3 4 5
Example 2: Calculating the Sum of First N Natural Numbers
- Declare variables
$n
and$sum
. - Assign a value to
$n
. - Initialize
$sum
to 0. - Use a while loop to calculate the sum of the first
$n
natural numbers. - Print the sum.
Perl Program
my $n = 10;
my $sum = 0;
my $i = 1;
while ($i <= $n) {
$sum += $i;
$i++;
}
print "Sum of first $n natural numbers is $sum\n";
Output
Sum of first 10 natural numbers is 55
Example 3: Reversing a Number
- Declare variables
$num
and$rev
. - Assign a value to
$num
. - Initialize
$rev
to 0. - Use a while loop to reverse the digits of
$num
. - Print the reversed number.
Perl Program
my $num = 12345;
my $rev = 0;
while ($num != 0) {
my $digit = $num % 10;
$rev = $rev * 10 + $digit;
$num = int($num / 10);
}
print "Reversed number is $rev\n";
Output
Reversed number is 54321