Gossamer Forum: General: Perl Programming: Help with project

I'm taking an introductory course into computer programming and I needed to write a Perl program for renaming files in a specified directory according to regular expression search and replace patterns given on the command line.

Has to support 4 optional command line flags -f, -u, -d, and -q to modify it's behavior. I made an error somewhere along the way, and I need someone to help me since I'm not a programmer at all :)

Here's the code, if anyone could fix it or write it in a different way of performing the task I'd greatly appreciate it. If not that's ok :). Here's what I wrote...

Code:
@args = (); 
$forceFlag = 0;   # -f 
$upcaseFlag = 0;  # -u 
$lowcaseFlag = 0; # -d 
$quietFlag = 0;   # -q  

$error = 0; 
# iterate through the arguments 
foreach $arg ( @ARGV ) 
{ 
 $first = substr($arg, 0, 1); 
 if ($first eq "-") 
 { 
  # we've found one or more switches 
  foreach $letter ( split('',$arg) ) 
  { 
   if ( $letter eq '-' ) 
   {  
    # do nothing  
   } 
   elsif ( $letter eq 'f' ) 
   { 
    $forceFlag = 1; 
   } 
   elsif ( $letter eq 'u' ) 
   { 
    $lowcaseFlag = 0; 
    $upcaseFlag = 1; 
   } 
   elsif ( $letter eq 'd' ) 
   { 
    $upcaseFlag = 0; 
    $lowcaseFlag = 1; 
   } 
   elsif ( $letter eq 'q' ) 
   { 
    $quietFlag = 1; 
   } 
   else 
   { 
    print "Invalid switch -$letter\n"; 
    $error = 1; 
   } 
  } 
 } 
 else 
 { 
  # we've found an argument 
  push(@args, $arg) 
 } 
} 
if ( $error ) 
{ 
 exit(1); 
}  

$numArgs = $#args + 1;  

if ( $numArgs < 1 ) 
{ 
 print "Error: no directory specified."; 
 exit(1); 
} 
else 
{ 
 $searchDir = $args[0]; 
}  

if ( $numArgs < 2 ) 
{ 
 print "Error: no search pattern specified.\n"; 
 exit(1); 
} 
else 
{ 
 $searchPattern = $args[1]; 
}  

if ( $numArgs == 3 ) 
{ 
 $replacePattern = $args[2]; 
}  

$totalfiles = 0; 
$validfiles = 0;  

opendir(D, $searchDir); 
@files = readdir(D); 
closedir(D); 
foreach $file (@files) 
{ 
 my $filename = $file; 
 my $originalName = $filename; 
    if ($file eq '.' || $file eq '..' || -d $file)  
    {    }  
    else  
    { 
   if ( $filename =~ /$searchPattern/ ) 
   { 
    $totalfiles++; 
    if ( $upcaseFlag ) 
    { 
     $filename = uc($filename); 
    } 
    if ( $lowcaseFlag ) 
    { 
     $filename = lc($filename); 
    } 
   } 
   my $resultName; 
   if ( $replacePattern ) 
   { 
    $resultName = renameFile($searchPattern, $replacePattern, $filename);     
    } 
    else 
    { 
     $resultName = $filename; 
    } 
   if ( $resultName ne $originalName ) 
   { 
    $validfiles++; 
    if ( $forceFlag ) 
    { 
     rename($searchDir . '/' . $originalName, $searchDir . '/' . $resultName); 
    } 
     if ( !$quietFlag ) 
    { 
      print $searchDir . '/' . $originalName . " -> " . $searchDir . '/' . $resultName . "\n"; 
     }  
   } 
  } 
}  

if ( $forceFlag ) 
{ 
 print "$validfiles file(s) were renamed out of $totalfiles file(s) that matched the search pattern.\n"; 
} 
else 
{ 
 print "$validfiles file(s) could be renamed out of $totalfiles file(s) that matched the search pattern.\n"; 
}  


sub renameFile 
{ 
 my $searchPattern = shift; 
 my $replacePattern = shift; 
 my $filename = shift; 
 $filename =~ s/$searchPattern/$replacePattern/g; 
 return $filename; 
}