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
to 100. Here's how it works. First,
rand is Perl's random number function, so
rand 100 gives us a random number in the range
from zero up to (but not including) 100. That is,
the largest possible value of that expression is something like
99.999.[397] Adding one gives a number
from 1 to 100.999, then the
int function truncates that, giving a result from
1 to 100, as we needed.
The commented-out line can be helpful 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 execute last.
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), and since the value as a number would be zero, the poor user
would get the message that their guess was too small. We might never
get to the string tests, in that case.
Another way to make the infinite loop here would be to use a naked
block with redo. It's no more or less
efficient; merely another way to write it. Generally, if you expect
to mostly loop, it's good to write while,
since that loops by default. If looping will be the exception, a
naked block may be a better choice.