Re: Printing largest number in array using loops and if statement

matze77,
Here are some reasons why sorting the array to find the maximum value is not a good idea:

You either change the order of the array, or waste memory making a copy
You spend extra cycles sorting when finding the max is more efficient O(N)

The implementation you have come up with is usually referred to as the high water mark algorithm. Usually, it looks more like this:

my $max;
for (@list) {
    $max = $_ if ! defined $max || $_ > $max;
}
[download]

If you know for that no value will be less than a certain number, you can set it to that (as you did with 0) or you can assign it to the first value in the list (as suggested elsewhere in this thread) and then loop through the rest of the list. Many would recommend not re-inventing the wheel and would point you to List::Util.

use List::Util 'max';

print max(@list), "\n";
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I wrote How A Function Becomes Higher Order which may be too advanced but keep the link around for when you are ready. Here are some extra credit ideas to make you consider how you might need to modify the water mark algorithm:

Consider you want to know the index of the largest element and not the value
Consider you want to the largest value and how many elements in the list are that value
Consider if instead of numbers you had strings
Consider if what you wanted to know was the element with the most characters

Cheers - L~R

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Re^2: Printing largest number in array using loops and if statement by matze77 (Friar) on Jan 17, 2010 at 08:39 UTC
Hmm. I must admit i do not fully understand that line of code, perhaps if written in more lines it is better to understand: `$max = $_ if ! defined $max \|\| $_ > $max;` [download] Could one say if $max is not defined (set to a value maybe this could occure on first iteration?). or $_ is greater than $_max?. Then $max is set to $_?	[reply] [d/l]
Re^3: Printing largest number in array using loops and if statement by dsheroh (Monsignor) on Jan 17, 2010 at 11:53 UTC
Yes, that is what it means. Any time you have `stmt if cond`, it can be rewritten as `if (cond) { stmt; }` [download] So, in this case, that line is equivalent to `if (! defined $max \|\| $_ > $max) { $max = $_; }` [download] Personally, I prefer the method of initializing `$max` to the first (defined) item in the list so as to avoid testing `!defined $max` on every pass. The performance benefit of avoiding that test is negligible, of course, but it reads more cleanly to me when you're able to just say "remember this as the highest value if it's greater than the previous highest value" without the extra "and a highest value has been previously set" clause.	[reply] [d/l] [select]