if-elsif-else statement in perl

if-elsif-else statement is used when we need to check multiple conditions. In this statement we have only one “if” and one “else”, however we can have multiple “elsif”. This is how it looks:

if(condition_1) {
   #if condition_1 is true execute this
   statement(s);
}
elsif(condition_2) {
   #execute this if condition_1 is not met and
   #condition_2 is met
   statement(s);
}
elsif(condition_3) {
   #execute this if condition_1 & condition_2 are
   #not met and condition_3 is met
   statement(s);
}
.
.
.
else {
   #if none of the condition is true
   #then these statements gets executed
   statement(s);
}

Note: The most important point to note here is that in if-elsif-else statement as soon as the condition is met, the corresponding set of statements get executed, rest gets ignored. If none of the condition is met then the statements inside “else” gets executed.

Example:

#!/usr/local/bin/perl

printf "Enter any integer between 1 & 99999:";
$num = <STDIN>;
if( $num <100 && $num>=1) {
   printf "Its a two digit number\n";
}
elsif( $num <1000 && $num>=100) {
   printf "Its a three digit number\n";
}
elsif( $num <10000 && $num>=1000) {
   printf "Its a four digit number\n";
}
elsif( $num <100000 && $num>=10000) {
   printf "Its a five digit number\n";
}
else {
   printf "Please enter number between 1 & 99999\n";
}

Output:

Enter any integer between 1 & 99999:8019
Its a four digit number