Paul Rousseau wrote:
Hello,
I want to open a text file, look for a specific string, replace it
with a new string, and write the line out to another file. For lines
not containing the specific string, I want to write out as is.
I was wondering if it is possible to do it with a map or splice or
grep command rather than a foreach loop.
Well, you didn't use a foreach loop in your sample below, you used a
while loop. But yes, it is possible to do it with a map, not a grep or
a splice.
Don't confuse the Perl grep with the Unix command. The perl grep works
on a single string, while the Unix grep repeats the same match over
multiple lines. Also, grep only finds strings; it doesn't do any
replacements.
A splice is for inserting or removing list elements - not what you want
to do.
Perhaps, I should be looking at some executable that replaces one
string with another within a file?
I have resorted to a foreach loop.
Nope, you used a while loop. You could have just as easily used a
foreach, though. Frankly, I think it's a perfectly appropriate
application of a while loop. I wouldn't say you 'resorted' to it.
Here is a snippet of my code:
$currnodename = "AMACHINE";
$oldnodename = "BMACHINE";
$infile = "$ENV{FT}\\qld\\$msg.qli";
$outfile = $ENV{TEMP} . "\\$task.tmp";
open (INFILE, "<$infile") || die "Can not open $infile";
open (OUTFILE, "+>$outfile") || die "Unable to open $outfile";
while ($inline = <INFILE>)
{
chomp $inline;
The chomp should not be there. You still want the newline in the output
string, right?
$inline =~ s/$oldnodename/$currnodename/g;
print OUTFILE $inline;
}
close INFILE;
close OUTFILE;
Here's your loop rewritten using map:
@lines = <INFILE>;
map { s/$oldnodename/$currnodename/g; $_ } @lines;
print OUTFILE @lines;
If for some reason you wanted to be able to reuse the original lines, so
you could do a different substitution on them in another pass, you could
preserve them thusly:
@inlines = <INFILE>;
map { s/$oldnodename/$currnodename/g; $_ } (@outlines = @inlines);
print OUTFILE @outlines;
Finally, here's your loop, actually written as a foreach:
@lines = <INFILE>;
foreach $line (@lines)
{
$line =~ s/$oldnodename/$currnodename/g;
}
print OUTFILE @lines;
--
Lyle Kopnicky
Software Project Engineer
Veicon Technology, Inc.
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