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Learn Perl from Scratch

Solution Review: Making a Calculator

Understand how to implement a simple calculator in Perl by using conditional statements to process user input and perform arithmetic operations based on operator conditions. Learn how to handle valid and invalid inputs effectively.

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Let’s look at the solution before jumping on to the explanation:

Perl
$num1 = 12.5;   # change values 
$num2 = 5.1;
$Operator = '-';   # change operator to check for when
print "Number 1 is: $num1 \n";
print "Number 2 is: $num2 \n";
print "Operator is: $Operator \n";
given ($Operator) {
    when ('+'){
        print "Answer is ";
        print $num1+$num2;
    }
    when ('-') {
        print "Answer is ";
        print $num1-$num2;
    }
    when ('*'){
        print "Answer is ";  
        print $num1*$num2;
    }
    when ('/'){
        print "Answer is ";  
        print $num1/$num2;
    }
    default{
        print "Wrong operator";
    }
}

Explanation

We have two variables $num1 and $num2 containing input numbers. We have another variable $Operator containing a character representing one of the desired mathematical operators. The $Operator is passed to the given statement and its value is matched with one of the when statements to perform the corresponding mathematical operation. In case of invalid input in $Operator, the default statement is executed.