Unexpected equality in Perl script

Question

There is an equality in my Perl subroutine that appears to be equal but should not be. I suspect there is an easy answer for this, but I'm new to Perl and probably did something I didn't fully understand. As you can imagine, there is more to the Perl code than I'm pasting, but I think the following code snippet should be sufficient to answer.

sub getJobStatus 
{
    my $ftps = shift;
    my $job_name = trim(shift);
    LogMessage("**********************************************************************\n");
    LogMessage("Getting JES status for job ${job_name}\n");
    LogMessage("**********************************************************************\n");

    # Note: the dir() method does not seem to listen to the supplied argument, and 
    # so returns all the jobs known. This is why all files must be parsed.
    my @job_files_found_lines = $ftps->dir($job_name)
        or die LogMessage ( "Cannot list for job ${job_name} message=$ftps->message()\n");

    my $parsed_job_status = ''; 
    my $counter=0;
    my @job_status_split = (split /.*\s+(JOB\d+)\s+([A-Z]+)\s+\d*\s+Spool Files/,$job_files_found_lines[$counter]);
    my $parsed_job_name=trim($job_status_split[1]);
    $parsed_job_status=$job_status_split[2];
    my $array_length = scalar @job_files_found_lines;
    LogMessage "\narray length=${array_length} expected_job_name=${job_name}\tjob_name=${parsed_job_name}\tjob_status=${parsed_job_status}\n";
    while($counter < $array_length && trim($parsed_job_name)!=$job_name) {
        @job_status_split = (split /.*\s+(JOB\d+)\s+([A-Z]+)\s+\d*\s+Spool Files/,$job_files_found_lines[$counter]);
        $parsed_job_name=trim($job_status_split[1]);
        LogMessage "\nexpected_job_name=${job_name}\tjob_name=${parsed_job_name}\tjob_status=${parsed_job_status}\n";
        $counter = $counter + 1;
    }
    if($job_name==$parsed_job_name) {
        LogMessage "Current job_name=${job_name} Found ${parsed_job_name} status=${parsed_job_status}\n";
        $parsed_job_status=$job_status_split[2];
    }
    return $parsed_job_status
}

My log result:

Wed Feb  3 08:07:21 2021:  ********************************************************************************
Wed Feb  3 08:07:21 2021:  Monitoring job status in repeated loop until job is completed (STATUS=OUTPUT)
Wed Feb  3 08:07:21 2021:  ********************************************************************************
Wed Feb  3 08:07:21 2021:  **********************************************************************
Wed Feb  3 08:07:21 2021:  Getting JES status for job JOB21680
Wed Feb  3 08:07:21 2021:  **********************************************************************
Wed Feb  3 08:07:21 2021:  
array length=19 expected_job_name=JOB21680  job_name=JOB19471   job_status=OUTPUT**
Wed Feb  3 08:07:21 2021:  Current job_name=JOB21680 Found JOB19471 status=OUTPUT
Wed Feb  3 08:07:21 2021:  
Wed Feb  3 08:07:21 2021:  **********************************************************************
Wed Feb  3 08:07:21 2021:  Getting JES output and storing file /host-dirs/out/JOB21680.out
Wed Feb  3 08:07:21 2021:  **********************************************************************

Please note the line in the log saying 'Current job_name=JOB21680 and Found JOB19471'. If it says found, it these two jobs should be the same. In the code snippet above, please look at trim($parsed_job_name)!=$job_name

https://stackoverflow.com/questions/1175390/how-do-i-compare-two-strings-in-perl — AKHolland, Feb 03 '21 at 15:50

score 4 · Accepted Answer · answered Feb 03 '21 at 15:19

4

!= is numerical comparison, those strings both evaluate as zero. String inequality operator is ne.

answered Feb 03 '21 at 15:19

score 3 · Answer 2 · answered Feb 03 '21 at 15:53

3

If you include use warnings in your code then it will tell you when you try to compare strings using the numeric comparison operator.

answered Feb 03 '21 at 15:53

Dave Cross

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I used use strict, but it tends to not flag errors until the relevant code gets executed. How is strict different than warnings? Thx in advance. – Woodsman Feb 04 '21 at 05:14
@Woodsman [strict](https://perldoc.perl.org/strict) looks for three specific problems. [warnings](https://perldoc.perl.org/warnings) reports on dozens of possible problems. You really need them both turned on. – Dave Cross Feb 04 '21 at 08:29

Unexpected equality in Perl script

2 Answers2