Newbie Perl question

[rhysmeister]

Something is up with my if statement...

$choice = <STDIN>; # read the choice from the keyboard
if($choice == "Y")
{
	stuff here;
}
elsif($choice == "N")
{
	stuff here
}

The statement always does the first if statement whatever is input. Probably an easy one!

 

[Nebbish]

Rhys,

== is used to compare numbers. Try using "eq" or "ne" (equal or not equal, respectively):

my $string = 'hello';

if($string eq "hello") {
print "equal";
} else {
print "not equal";
}

 

[toolkit]

Also, don't forget to chomp any end-of-line characters from the input string.

chomp($choice = <STDIN>);

Cheers, Neil

 

[duncdude]

chomp ($choice = <STDIN>); # read the choice from the keyboard

if ($choice eq "Y") {
  print "YES\n";
} else {
  print "NO\n";
}

Kind Regards
Duncan

 

[rhysmeister]

Wow quick! Thanks. Done that but it just skips to my else section of the staement.

print("Configure General options? Y/N");
$choice = <STDIN>; # read the choice from the keyboard
if($choice eq 'Y')
{
	
}
elsif($choice eq 'N')
{	
	
}
else # have to finish with an else!!!
{
	print "An error has occured!";
}

 

[duncdude]

are you using a lowercase 'y' rather than 'Y'?


Kind Regards
Duncan

 

[rhysmeister]

Ah right, I remember, use chomp to get rid of the newline character!! Thanks to both of you!

 

[duncdude]

chomp ($choice = <STDIN>); # read the choice from the keyboard

if (lc($choice) eq "y") {
  print "YES\n";
} else {
  print "NO\n";
}

Kind Regards
Duncan

 

[Geekatron]

Are you allowing lowercase input? If 'n' or 'y' is entered, your else statement WILL always be reached. Try this instead:

print("Configure General options? Y/N");
$choice = <STDIN>; # read the choice from the keyboard
if($choice =~ /^Y$/i)
{
    
}
elsif($choice =~ /^N$/i)
{    
    
}
else # have to finish with an else!!!
{
    print "An error has occured!";
}

--G

 

[Geekatron]

Or use Duncan's solution, which is much more elegant than mine. *sigh*

--G

 

[rhysmeister]

Thanks all of you, got to be the fastest forums I've ever been on! Is there an uppcase() function like C has?

 

[toolkit]

uc - uppercase
lc - lowercase
lcfirst - lowercase first letter
ucfirst - uppercase first letter

 

[duncdude]

by the way...

you need to chomp the input to remove the line ending

eq is used for textual comparisons and == for numeric

it probably makes sense to reduce if statements by just using the else instead of another elsif


Kind Regards
Duncan

 

[Geekatron]

You can also use metacharacters in strings to accomplish the same thing:

$mystring = "fee \Ufi fo fum";
print $mystring';

output:
fee FI FO FUM

or

$mystring = "\ufee fi fo fum";
print $mystring';

output:
Fee fi fo fum

\U - converts everything after it in a string to uppercase
\L - converts everything after it in a string to lowercase
\u - converts next character only to uppercase
\l - converts next character only to lowercase

These are handier if you want to make multiple changes in the same string:

# capitalize each word
$mystring = "\ufee \ufi \ufo \ufum";

If you want to convert entire strings one way or the other, though, I find lc and uc to be syntactically neater.

Even if Duncan did remember them and I didn't.

But I'm not bitter. ;-)

--G

 

[rhysmeister]

Thanks!!!