Perl While Statement - perl

Question

Okay, so here's my final question (for the day): I am trying to get my program to search through a document. If the document has the word "unsuccessful" in it anywhere, then the program will search for the word "error" and record all instances of error. However, I am having a hard time making the two dependent on one another. Please help! I am very very new to Perl (this is only my second day using it) so the more detail/comments you can provide, the better! Here is my current code, I am aware it does not run right now:
#!/usr/local/bin/perl
my $argument1 = $ARGV[0];
my $argument2 = $ARGV[1];
open (LOGFILE, "<$argument1") or die "Can't find file";
open FILE, ">>$argument2" or die $!;
while (<LOGFILE>){
if {(/Unsuccessful/){
while(<LOGFILE>){
if (/Error/){
print FILE "ERROR in line $.\n" ;
}
}
}
}
}
close FILE;
close LOGFILE;

Answer 1

Check for "Unsuccessful" and "Error" in one loop and at the end print error findings if "Unsuccessful" has been found...
my $argument1 = $ARGV[0];
my $argument2 = $ARGV[1];
open (LOGFILE, "<$argument1") or die "Can't find file";
open (FILE, ">>$argument2") or die $!;
my $unsuccessful = 0;
my #errors = ();
while (<LOGFILE>) {
if (/Unsuccessful/i) {
$unsuccessful = 1;
}
if (/Error/i) {
push(#errors, "ERROR in line $.\n");
}
}
if ($unsuccessful) {
print $_ for #errors;
}
Switch /i applies for case-insensitive search, so remove it from the code above if not wanted.

Answer 2

Using
<LOGFILE>
multiple times is probably not what you want. The more immediate cause of your trouble is probably a badly placed "{".
It looks like you expect "Error" to always appear later than "Unsuccessful", right?
Try
my $argument1 = $ARGV[0];
my $argument2 = $ARGV[1];
open (LOGFILE, "<$argument1") or die "Can't find file";
open FILE, ">>$argument2" or die $!;
my $unsuccessful = 0;
while (<LOGFILE>){
if ($unsuccessful) {
if (/Error/) { print FILE "ERROR in line $.\n"; }
}
else {
if (/Unsuccessful/) { $unsuccessful = 1; }
}
}
close FILE;
close LOGFILE;

Answer 3

You are committing a grave mistake by taking step 5 before step 1. You're not using the strict and warning pragmas in your code. In fact, the code you posted doesn't compile.
As for the problem in question, provided that you want to parse each file only once (as a good programmer should strive to do), you should parse in two modes: (1) the mode where unsuccessful has been detected, and the mode where it has not yet been detected. The former will have the job of outputting lines, while the latter won't.
Now I'd suggest getting back to some basics and not taking steps in advance. I've taken step 5 before step 1 many times in the past myself, and it was a mistake each and every time.