Notes from Wednesday September 11, 2013

The if-statement:



#!/usr/bin/perl
use strict;

my $number;

 

print "Enter a number ";
chomp($number=<STDIN>);

 

if ($number < 50)
{
     print "Your number is less than 50\n";
     print "you may now leave class\n";
}
elsif( $number>50 and $number <100)
{
     print "the number is between 50 and 100\n";
}
else
{
     print "Your number is greater than 100\n";
     print "You need to program more perl\n";
}


if ($average>=90)
{
     $grade="A";
}
elsif( $average>=80)      # note: we don't need to check if $average<90 here because it must be if we made it here
{
 $grade="B";
}
elsif ( $average>=70)
{
 $grade="C";
}
else # no boolean expression here!!!
{
 $grade="D";
}

 
if-state and a while loop:



#!/usr/bin/perl
use strict;

 

my $average;
my $grade;
my $quiz1;
my $quiz2;
my $quiz3;
my $name;


while ( $name ne "stop" )
{
    print "Please enter your name [stop to exit execution] ";
    chomp($name=<STDIN>);

 if ($name ne "stop")
 {

    # get the three quiz scores

   print "Enter quiz score ";
   chomp($quiz1=<STDIN>);

   print "Enter quiz score ";
   chomp($quiz2=<STDIN>);

   print "Enter quiz score ";
   chomp($quiz3=<STDIN>);
   
    # Calculate the average

   $average=($quiz1+$quiz2+$quiz3)/3;

 

 # output grade

   if ($average>=90)
   {
     $grade="A";
   }
   elsif( $average>=80)
   {
     $grade="B";
   }
   elsif ( $average>=70)
   {
     $grade="C";
   }
   else # no boolean expression here!!!
   {
     $grade="D";
   }

   print "$name received a grade of $grade\n";

 } 

}
 
print "good-bye\n";

Loops to add up infinite series


#!/usr/bin/perl

use strict;

my $sum1=0;
my $sum2=0;


my $count=1;
my $count2=1;

while($count<=10000000)
{
    $sum1=$sum1+ (1/$count);  # here we calculate    1  + 1/2   +  1/3   + 1/4  + 1/5 +
    $sum2=$sum2+ (1/$count2);# here we calculate    1  + 1/2  +   1/4    + 1/8  + 1/16

 
    $count2=$count2*2;
    $count=$count+1;

}

print "Sum 1 is $sum1\n";
print "Sum2 is $sum2\n";