I try to read in a file and write out a new file with increased number at the end of each line. And I can set the initial value and increased constant from inputs.

input file:
text1
text2
text3
...
text100

if I set initial value is 10, and increased constant is 0.4
output file:
text1 10
text2 10.4
text3 10.8
...
text100 49.6

Code:
if ($#ARGV != 3) {
print "usage: do inputfile initial step outputfile\n";
exit;
}

$infile = $ARGV[0];
$initial = $ARGV[1];
$cons = $ARGV[2];
$outfile = $ARGV[3];

open(OF, $infile);
open(NF, ">$outfile");

my $offset = $initial;

# read in each line of the file
while ($line = <OF>) {
$line =~ s/$/ $offset/;
$offset += $cons;
print NF $line;
}

close(OF);
close(NF);

But my output like:
text1 10
text2 10.4
text3 10.8
...
text54 31.1999999999999
text55 31.5999999999999
text56 31.9999999999999
text57 32.3999999999999
text58 32.7999999999999
...
text100 49.5999999999999

How to keep 1 decimal digit output? And why get this result?

Thanks,

use sprintf or printf:

but I need show text1 ~ text100 in output file, the increased number be added at the end of each text.

my example is a helping hand, not a complete solution. But what you want to do should be very easy, give it try.