Problem with print statement

[jt2]

Hello Perl Gurus!

I'm quite a perl neophyte so I'm looking for help understanding why print doesn't print correctly. This may be a totally stupid error....


He is my program. What it is doing is parsing a file of comma seperated values and trying to extract the address field every time the clock field transitions from a zero to a one.

[code=perl]
#! /usr/bin/perl

open(LISTING, "$ARGV[0]");

$line_count = 0;
$value_count = 0;
# skip first line of file
$line_read = <LISTING>;

$search_val = 1;
$array_index = 0;
# while not at end of file
while ($line_read = <LISTING>) {
$line_count++;

chop ($line_read);

# get values from line
($time, $status, $phase, $addr, $bft, $clk) = split(",", $line_read);

print "clock: ", $clk, " search value: ", $search_val, "\n";

#look for current search_val of clk
if ($clk == $search_val) {
# on the rising edge of the clock, capture the addr value
if ($clk == 1) {
#print "line count: " $line_count "\n" ;
$lst[$array_index++] = $addr;
$value_count++;

#toggle the clock value we are searching for
if ($search_val eq 1) {
$search_val = 0;}
else {
$search_val = 1;}

}
else {
#toggle the clock value we are searching for
if ($search_val eq 1) {
$search_val = 0;}
else {
$search_val = 1;}
}

}
else {
print "In Else, search value: ", $search_val, " clock value: ", $clk, "\n";
}

}
print "line_count : ", $line_count, " value_count: ", $value_count, "\n" ;

foreach $val (@lst) {
print $val, ",";
}
print "\n";
[/code]


Here is the data file I am using:
Time,STAT,CMD,A DDR,TRIG,CLK
1.1 ns,0,0,0,1,0
1.667 ns,0,0,0,1,1
1.667 ns,0,0,4,1,0
1.667 ns,0,0,104,1,0
88.333 ns,0,0,104,1,1
1.667 ns,0,0,104,1,1
48.333 ns,0,0,104,1,0
1.667 ns,0,0,26,1,0
85.000 ns,0,0,26,1,1
1.667 ns,0,0,26,1,1


And here is the console output:
% perl extract.pl tst.csv
search value: 1
In Else, search value: 1 clock value: 0
search value: 1
search value: 0
search value: 1
In Else, search value: 1 clock value: 0
search value: 1
search value: 0
In Else, search value: 0 clock value: 1
search value: 0
search value: 1
In Else, search value: 1 clock value: 0
search value: 1
search value: 0
In Else, search value: 0 clock value: 1
line_count: 10 value_count: 3
0,104,26,


What is wrong with this print statement in that "clock: " is never printed?
print "clock: ", $clk, " search value: ", $search_val, "\n";

[KevinADC]

maybe the file is not opening, do this:

open(LISTING, $ARGV[0]) or die "Can't open $ARGV[0]: $!";

[jt2]

No, the file is opening and being processed just fine, and this program is working in that I am extracting the values that I want.

I'd like to understand why that print statement doesn't work correctly. I was adding print statements all over the place last night to try and debug this program, and I found that I had to debug the print statements! Doh!

[KevinADC]

What are you expecting to get printed?

[jt2]

The print statement is:

print "clock: ", $clk, " search value: ", $search_val, "\n";


so I would expect to see something like:

clock: 1 search value: 0


to be printed out. The console output I get is:

% perl extract.pl tst.csv
search value: 1
In Else, search value: 1 clock value: 0
search value: 1
search value: 0
search value: 1
etc......

What happened to the "clock: $clk portion from the print statement
print "clock: ", $clk, " search value: ", $search_val, "\n";

[eWish]

I would suggest that you use the strict and warnings pargmas for starters. However, that would not necessarily show you your problem. Also, when you want to make a numerical comparison you would use == in lieu of eq which is for strings. Then it appears that chop should be chomp. Chomp removes a line endings and chop removes the last character. Since the value for clock is only one character long I would say that that is your problem.

Give that a try and see where you get.

--Kevin

[jt2]

Ok, so its obvious that no one would even try running the program to verify the error.

So, how about a smaller test program?

#! /usr/bin/perl


#open input file
#open(LISTING, "$ARGV[0]") or die "Can't open $ARGV[0]: $!";
open(LISTING, "$ARGV[0]");

#skip first line of file
$line_read = <LISTING>;

$line_read = <LISTING>;
print $line_read;

$search_val = 1;

chomp ($line_read);
print "$line_read\n";

# get values from line
($time, $status, $phase, $addr, $bft, $clk) = split(",", $line_read); 

print $line_read;

print "clock: ", $clk, "   search value: ", $search_val, "\n";
print "clock:  $clk   search value:  $search_val\n";
print "search value:  $search_val clock:  $clk   \n";
    
print "$time\n";
print "$status\n";
print "$phase\n";
print "$addr\n";
print "$bft\n";
print "$clk\n";

Here is the file read by the program:

junk line
1.1 ns,0,0,0,1,0
1.1 ns,0,0,0,1,0
1.1 ns,0,0,0,1,0


And here is the output from the program execution:

% perl test.pl tst2.csv
1.1 ns,0,0,0,1,0
1.1 ns,0,0,0,1,0
search value: 1
search value: 1
rch value: 1 clock: 0
1.1 ns
0
0
0
1
0


Why do these print statements not work correctly??

print "clock: ", $clk, "   search value: ", $search_val, "\n";
print "clock:  $clk   search value:  $search_val\n";
print "search value:  $search_val clock:  $clk   \n";

[KevinADC]

When I run your test script I get this:

1.1 ns,0,0,0,1,0
1.1 ns,0,0,0,1,0
1.1 ns,0,0,0,1,0clock: 0   search value: 1
clock:  0   search value:  1
search value:  1 clock:  0   
1.1 ns
0
0
0
1
0
1.1 ns,0,0,0,1,0
1.1 ns,0,0,0,1,0
1.1 ns,0,0,0,1,0clock: 0   search value: 1
clock:  0   search value:  1
search value:  1 clock:  0   
1.1 ns
0
0
0
1
0
1.1 ns,0,0,0,1,0
1.1 ns,0,0,0,1,0
1.1 ns,0,0,0,1,0clock: 0   search value: 1
clock:  0   search value:  1
search value:  1 clock:  0   
1.1 ns
0
0
0
1
0


clock:    search value: 1
clock:     search value:  1
search value:  1 clock:

the input was:

1.1 ns,0,0,0,1,0
1.1 ns,0,0,0,1,0
1.1 ns,0,0,0,1,0


I am stumped why your code prints out something different.

[jt2]

Funny stuff huh?

I've tried running this script on two different machines, one Unix box running Solarix9 and perl version 5.6.1, and a Linux box running (unknown) version of Red Hat linux with (unknown) version of perl.

They both responded the same odd way...

Hmm, I AM accessing these machines by running EXCEED on my PC, which is an X windows utility.

[jt2]

KevinADC, why did your output have three copies of the expected output?

[KevinADC]

because the input was three lines

[jt2]

Hmm, yeah, but I didn't have a loop in my smaller test program.

Did you add a loop to test all three lines?

Also, did you notice in your output that the third line didn't print out the clock value correctly?

[KevinADC]

Hmm, yeah, but I didn't have a loop in my smaller test program.

Did you add a loop to test all three lines?

Also, did you notice in your output that the third line didn't print out the clock value correctly?

Yes, I looped through a three line "file". You can ignore that last part of the output, I should have left that out. Lines 1 thru 33 are the valid output, after that is a side-affect of running the code in my IDE and using __DATA__ instead of an external file.