#usr/bin/perl

if ($#ARGV == -1)
{
print("Please enter a filename: ");
$filename = <STDIN>;
chomp($filename);
}
else
{
$filename = $ARGV[0];
}


if ($filename !~ m/[a-zA-Z]{0,7}\.TXT$/i)
{
die("File format not valid\n");)
}


if ($filename !~ m/\.TXT$/i)
{
$filename .= ".TXT";
}

if (-e $filename)
{
die("File does not exist\n");
}

if (-s $filename)
{
die("File is empty\n");
}

while ($ch = getc(READFILE))
{
if ($ch eq "?" || $ch eq "!" || $ch eq ".")
{
 $sentences++;
}
}

close(READFILE);

print("Sentences:    $sentences\n");