Shell Programming and Scripting

Dear all,

I am new to perl script and would need some help for my 1st script. I wrote a script to search sprintf(buf,"%s", sourcestring) and replace with snprintf(buf, sizeof(buf),"%s", sourcestring). As snprintf() requires an extra argument, so it is not a simple search-and-replace. I need to match sprintf(), grab the first argument and use it for the second argument. This script also need to check and ensure that the destination string, the first argument to sprintf(), is a characeter array and not a pointer before doing the replacement.

My code is as follows:
#!/usr/bin/perl
# Search and Replace
if ($ARGV[0] eq "")
{
print "usage: file1 file2 etc. or wildcards (replaces originals in place\n)";
}
else
{
$totrep = 0;
$totfil = 0;
foreach $filename (@ARGV)
{
if(-T $filename)
{
$totrep += &process($filename);
$totfil++;
}
}
print "$totfil files, $totrep replacements\n";
}
sub process
{
$fn = $_[0];
undef $/; #to grab entire file at once
print STDERR "$fn"; #show currnt file name
open (INFILE, $fn);
$q = <INFILE>;
close INFILE;
$/ = "\n";
$sum = 0;

if ($q =~ m/char\s*([\w]+)/i)
{

$sum = ($q =~ s/\bsprintf\(([\w]+),/snprintf\(\1,sizeof\(\1\),/ig);
}
if ($sum > 0)
{
open (OUTFILE,">$fn");
print OUTFILE $q;
close OUTFILE;
print " $sum replacement(s)";
}
print "\n";
return $sum;
}

However, there are some error for checking the char string (once the 1st occurence of char string passed the check, it will do search-and-replace for all sprintf() to snprintf() in the file). I would need help to identify what's wrong with the script. Thanks all.

lets look at the regexp:

$sum = ($q =~ s/\bsprintf\(([\w]+),/snprintf\(\1,sizeof\(\1\),/ig);

you have [\w]+ which is the same as \w+ but the problem is that you are also looking for non-word characters in the string, but \w only matches a-zA-Z0-9_ so characters like % will never be found in the search string. Or have I misunderstood what you are doing?