Answer to Chapter 10 Exercise
Here’s one way to do it:
my $secret = int(1 + rand 100); # This next line may be un-commented during debugging # print "Don't tell anyone, but the secret number is $secret.\n"; while (1) { print "Please enter a guess from 1 to 100: "; chomp(my $guess = <STDIN>); if ($guess =~ /quit|exit|^\s*$/i) { print "Sorry you gave up. The number was $secret.\n"; last; } elsif ($guess < $secret) { print "Too small. Try again!\n"; } elsif ($guess = = $secret) { print "That was it!\n"; last; } else { print "Too large. Try again!\n"; } }
The first line picks out our secret number from
1
to100
, and here’s how it works. First,rand
is Perl’s random number function, sorand 100
gives us a random number in the range from 0 up to (but not including) 100. That is, the largest possible value of that expression is something like99.999
.[374] Adding one gives a number from1
to100.999
, and theint
function truncates that, giving a result from1
to100
, as we needed.The commented-out line can help during development and debugging, or if you like to cheat. The main body of this program is the infinite
while
loop. That will keep asking for guesses until we executelast
.It’s important that we test the possible strings before the numbers. If we didn’t, do you see what would happen when the user types
quit
? That would be interpreted as a number (probably giving a warning message if warnings were turned on); since the value as a number would be zero, the poor users would get the ...
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