RE: Padding out strings.

My preferred method:

#!/usr/bin/perl

# padding a string with leading zeros
# - $num is the number to be padded
# - $pad is the total number of digits you want in the result

$num = "345";
$pad = 5;
$paddednum = &pad_num($num, $pad);
print "num is $num, padded num is $paddednum\n";

exit(0);

##############################

sub pad_num {

# how it works:
#
# "0"x$pad yields ($pad) zeros, i.e. "0" x 5 yields "00000" ...
# this is prepended to $num, yielding a string with ($pad) zeros
# and the number. This becomes the first arg to the substr fn
#
# ($pad * -1) is the second arg to substr ... when 2nd arg to
# substr is negative, substr counts backward from the end of the string
#
# $pad is the third arg to substr
#
# thus if $pad is 5 and $num is 345,
# result is substr( "00000345", -5, 5 ) or "00345"

my ($num, $pad) = @_;
my($paddednum) = substr( (("0"x$pad).$num), ($pad*-1), $pad );
return $paddednum;

}

Comment on RE: Padding out strings.

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Re: RE: Padding out strings. by softworkz (Monk) on Jul 30, 2001 at 18:40 UTC
I've had to do something like this awhile back so here's my baby perl version. Have fun! #!/usr/bin/perl-w use win32; use strict; # uncomment this out if you want to input the amount of chars #if($#ARGV < 0) { # die "usage: program.pl <padding chars> \n" # . "for example: program.pl 30\n" #} #my $padlength = $ARGV[0]; my $in_name=$ARGV[0]; open(FILE,"numbers.txt") \|\| die "numbers.pl can't open file: $!"; open(OUTPUT,">numberdump.txt") or die "numbers.pl can't open file: $!" +; while (<FILE>) { chomp; # sample input: # UserID Date # 423Hm54 ATHENA02 10/1/2000 # 123456Dh60 ATHENA02 10/1/2000 # 18Dh60 ATHENA02 10/2/2000 # 10Jch6 ATHENA05 10/2/2000 # 54321Hh24 ATHENA05 10/2/2000 # 21Mwm22 ATHENA03 10/2/2000 #Look only at the summary lines where $_ == 2000 next unless ($_ =~ /2000/i); # this is to clean up the first variable length field my $padchar = "0"; my $count = length($_); my $padlength = 30; # comment this out if using ARGV $padchar = $padchar x ($padlength-$count); print $padchar, $_, "\n"; print OUTPUT $padchar, $_,"\n"; } close FILE; close OUTPUT; # sample output: # 000423Hm54 ATHENA02 10/1/2000 # 123456Dh60 ATHENA02 10/1/2000 # 000018Dh60 ATHENA02 10/2/2000 # 000010Jch6 ATHENA05 10/2/2000 # 054321Hh24 ATHENA05 10/2/2000 # 00021Mwm22 ATHENA03 10/2/2000 [download]	[reply] [d/l]

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Re: RE: Padding out strings.
by softworkz (Monk) on Jul 30, 2001 at 18:40 UTC

#!/usr/bin/perl-w
use win32;
use strict;

# uncomment this out if you want to input the amount of chars
#if($#ARGV < 0) {
#  die "usage: program.pl <padding chars> \n"
#    . "for example: program.pl 30\n"
#}
#my $padlength = $ARGV[0];  

my $in_name=$ARGV[0];
open(FILE,"numbers.txt") || die "numbers.pl can't open file: $!";
open(OUTPUT,">numberdump.txt") or die "numbers.pl can't open file: $!"
+;
while  (<FILE>) {
    chomp;

# sample input:
# UserID             Date
# 423Hm54 ATHENA02 10/1/2000 
# 123456Dh60 ATHENA02 10/1/2000 
# 18Dh60 ATHENA02 10/2/2000 
# 10Jch6 ATHENA05 10/2/2000 
# 54321Hh24 ATHENA05 10/2/2000 
# 21Mwm22 ATHENA03 10/2/2000 

#Look only at the summary lines where $_ == 2000
next unless ($_ =~ /2000/i);  

    # this is to clean up the first variable length field
    my $padchar = "0";
    my $count = length($_);
    my $padlength = 30;   # comment this out if using ARGV
    $padchar = $padchar x ($padlength-$count);
    print $padchar, $_, "\n";
    print OUTPUT $padchar, $_,"\n";

}
close FILE;
close OUTPUT;

# sample output:
# 000423Hm54 ATHENA02 10/1/2000 
# 123456Dh60 ATHENA02 10/1/2000 
# 000018Dh60 ATHENA02 10/2/2000 
# 000010Jch6 ATHENA05 10/2/2000 
# 054321Hh24 ATHENA05 10/2/2000 
# 00021Mwm22 ATHENA03 10/2/2000
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