Use of uninitialized value within #spl in substitution (s///) - arrays

Question

I am getting following error while running the script.
Use of uninitialized value in print at PreProcess.pl line 137.
Use of uninitialized value within #spl in substitution (s///) at PreProcess.pl line 137.
Is there any syntax error in the script?
(Running it in Windows - Strawberry 64 last version)
my $Dat=2;
my $a = 7;
foreach (#spl) {
if ( $_ =~ $NameInstru ) {
print $spl[$Dat] =~ s/-/\./gr, " 00:00; ",$spl[$a],"\n"; # data
$Dat += 87;
$a += 87;
}
}
inside of array i hve this type of data
"U.S. DOLLAR INDEX - ICE FUTURES U.S."
150113
2015-01-13
098662
ICUS
01
098
128104
14111
88637
505
13200
50
269
43140
34142
1862
37355
482
180
110623
126128
17480
1976
1081
-3699
8571
-120
646
50
248
1581
-8006
319
2093
31
-30
1039
1063
42
18
100.0
11.0
69.2
0.4
10.3
0.0
0.2
33.7
26.7
1.5
29.2
0.4
0.1
86.4
98.5
13.6
1.5
215
7
.
.
16
.
.
50
16
8
116
6
4
197
34
28.6
85.1
41.3
91.3
28.2
85.1
40.8
91.2
"(U.S. DOLLAR INDEX X $1000)"
"098662"
"ICUS"
"098"
"F90"
"Combined"
"U.S. DOLLAR INDEX - ICE FUTURES U.S."
150106
2015-01-06
098662
ICUS
01
098
127023
17810
80066
625
12554
0
21
41559
42148
1544
35262
452
210
109585
125065
17438
1958
19675
486
23911
49
2717
0
-73
9262
-5037
30
5873
270
95
18439
19245
1237
431
100.0
14.0
63.0
0.5
9.9
0.0
0.0
32.7
33.2
1.2
27.8
0.4
0.2
86.3
98.5
13.7
1.5
202
7
.
.
16
0
.
48
16
9
105
6
4
185
34
29.3
83.2
43.2
90.6
28.9
83.2
42.8
90.5
"(U.S. DOLLAR INDEX X $1000)"
"098662"
"ICUS"
"098"
"F90"
"Combined"

Answer 1

You are probably trying to load a file of data sets of a size of 87 lines each into an array, and then you get an error at the end of your data, when you try to read outside of the last array index.
You can probably solve it by iterating over the array indexes instead of the array values, e.g.
my $Dat = 2;
my $a = 7;
my $set_size = 87;
for (my $n = 0; $n + $a < #spl; $n += $set_size) {
if ( $spl[$n] =~ $NameInstru ) {
print $spl[$n + $Dat] =~ s/-/\./gr, " 00:00; ",$spl[$n + $a],"\n"; # data
}
}
While this might solve your problem, it might be better to try and find a proper way to parse your file.
If the records inside the input file are separated by a blank line, you can try to read whole records at once by changing the input record separator to "" or "\n\n". Then you can split each element in the resulting array on newline \n and get an entire record as a result. For example:
$/ = "";
my #spl;
open my $fh ...
while (<$fh>) {
push #spl, [ split "\n", $_ ];
}
...
for my $record (#spl) {
# #$record is now an 87 element array with each record in the file
}

Answer 2

TLP's solution of iterating over the indexes of an array, incrementing by 87 at time is great.
Here's a more complex solution, but one that doesn't require loading the entire file into memory.
my $lines_per_row = 87;
my #row;
while (<>) {
chomp;
push #row, $_;
if (#row == $lines_per_row) {
my ($instru, $dat, $a) = #row[0, 2, 7];
if ($instru =~ $NameInstru) {
print $dat =~ s/-/\./gr, " 00:00; $a\n";
}
#row = ();
}
}