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";