How to format a string or number with leading zeros?

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January 13th, 2001, 03:47 PM

kumars

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I am new to Perl. Trying to print out a number padded with leading zeros.

example:
$num = 123;

the output/print should have 00123.Total width of 5 padded with leading zeros.
Appreciate any help in this direction.

Thank you

January 13th, 2001, 04:09 PM

mickalo

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Quote:

Originally posted by kumars
I am new to Perl. Trying to print out a number padded with leading zeros.

example:
$num = 123;

the output/print should have 00123.Total width of 5 padded with leading zeros.
Appreciate any help in this direction.

Thank you

Try this:

Code:

my $num = "123"; 
$num = sprintf("%5d", $num);
$num=~ tr/ /0/;

this will "pad" the variable $num with leading "0"'s up to 5 characters: IE 00123 or 01234. If for some reason the $num contains a total of 5 characters, then no "0"'s would be added.

Hope this helps

Mickalo

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January 13th, 2001, 05:07 PM

kumars

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Great, it worked.

Thank you Mickalo,

It worked.Thanks again for the fast response.

January 13th, 2001, 05:49 PM

mickalo

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Hey,.. No problems

Glad to help when I can.

Mickalo

January 18th, 2007, 12:54 PM

Correction

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Quote:

Originally Posted by mickalo

Try this:

Code:

my $num = "123"; 
$num = sprintf("%5d", $num);
$num=~ tr/ /0/;

Code:

my $num = "123"; 
$num = sprintf("%05d", $num);

January 19th, 2007, 01:57 AM

PlanB

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You can do "substr("00000$num",-5)" as well.
It might be a bit faster though it won't be attractive.

January 19th, 2007, 02:39 AM

KevinADC

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Quote:

Originally Posted by Correction

Code:

my $num = "123"; 
$num = sprintf("%05d", $num);

hehehe... you corrected a 6 year old post! That must be a record.

May 25th, 2010, 09:17 AM

wdrev

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Quote:

Originally Posted by KevinADC

hehehe... you corrected a 6 year old post! That must be a record.

It helped me.

January 29th, 2013, 11:40 PM

khirin

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Quote:

Originally Posted by wdrev

It helped me.

3 Years later, It helped me too

#10

February 2nd, 2013, 06:50 AM

hofjseph

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It helped me too

#11

February 4th, 2013, 05:20 PM

Laurent_R

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Hi,
well I had a very similar problem today at work and I originally used a solution similar to what I thought was the best solution shown so far:

Perl Code:

Original - Perl Code
my $num = "123"; $num = sprintf("%05d", $num);

my $num = "123"; 
$num = sprintf("%05d", $num);

And it does work as long as you are guaranteed to have digits in your input. Except that when I ran the program, I got an error message because there were a couple of cases where I have letters rather than digits in my input file. And the sprinft formatting string fails in this case. These letters are not really an error, but the indication of a special exception condition that still needs to be handled.

So I think I'll change it to:

Perl Code:

Original - Perl Code
my $num = "123"; $num = sprintf("%05s", $num);

my $num = "123"; 
$num = sprintf("%05s", $num);

so that if my input is "foo", I'll get "00foo" which, even if it does not seem to make too much sense, is what I need in this case to have the logic of my program working in this case (I need to pad my data with 0's at the beginning of my value, in order to be able to compare data from 2 different files with similar values but different formatting conventions.

This was just to say that the "%05s" format string might just be more general than "%05d" in some real life situations. I haven't tested it against my data yet, I'll do that tomorrow morning.

How to format a string or number with leading zeros?

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