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# Getting confused with 2d arrays

Posted on 2008-06-11
Medium Priority
150 Views
Hi,

I just built a 2D array, and I want to iterate over all elements for printing. I tried this:

for (\$i = 0; \$i < @rows; \$i++) {
for (\$j = 0; \$j < @rows[\$i]; \$j++) {
print(\$rows[\$i][\$j], "  ");
}
print("\n");
}

where @rows is my 2D array, but the script just executes in an infinite loop. I'm guessing the problem is:

\$j < @rows[\$i]

in that statement I mean to say the length of the 1d array in element \$i of the 2D array. What's the right syntax for it?

thanks
0
Question by:DJ_AM_Juicebox
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LVL 39

Expert Comment

ID: 21761331

``````for(my \$i = 0; \$i < @rows; \$i++) {
for (my \$j = 0; \$j < @{\$rows[\$i]}; \$j++) {
print(\$rows[\$i][\$j], "  ");
}
print("\n");
}
``````
0

LVL 13

Expert Comment

ID: 21761414
Here you'll find how to iterate the 2d array with example http://icfun.blogspot.com/2008/03/perl-two-dimensional-array-handling.html
0

Author Comment

ID: 21762045
Ehh still seems to just loop endlessly. Here's my entire script:

my @rows = ( [2, 4, 6],
[3, 6, 9],
);

for (my \$i = 0; \$i < @rows; \$i++) {
for (my \$j = 0; \$j < @{rows[\$i]}; \$j++) {
print(\$rows[\$i][\$j], "  ");
}
}
0

LVL 39

Accepted Solution

ID: 21762470
You are missing the \$ in front of rows[\$i].  It should be:
The @{\$rows[\$i]} means:
take \$rows[\$i], which is a reference to an array
Then take that array

Then the \$j < mean interpret that array in scalar context, which means return the number of elements in the array.
``````my @rows = ( [2, 4, 6],
[3, 6, 9],
);

for (my \$i = 0; \$i < @rows; \$i++) {
for (my \$j = 0; \$j < @{\$rows[\$i]}; \$j++) {
print(\$rows[\$i][\$j], "  ");
}
}
``````
0

Author Comment

ID: 21763025
ok you're right, thanks.
0

LVL 84

Expert Comment

ID: 21763984
It may be safer to itterate
for my \$i( \$[ .. \$#rows ){ for my \$j ( \$[ .. \$#{\$rows[\$i]} )
Or a simpler way is
print "@\$_\n" for @rows;
0

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