Find highest number in array

[Patrick Taylor]

$my_array is an array of 3-figure numbers which is from a MySQL query using GROUP BY.

echo $my_array; prints all the 3-figure numbers joined together, eg: 456184562784825675983726 etc etc (bolded just for clarification).

How can I find the highest 3-figure number with PHP?

[Chillijam]

$my_array is an array of 3-figure numbers which is from a MySQL query using GROUP BY.

echo $my_array; prints all the 3-figure numbers joined together, eg: 456184562784825675983726 etc etc (bolded just for clarification).

How can I find the highest 3-figure number with PHP?

There may be a built-in function that will do this, but I don't know it.

Try

$maxnum = 0;
foreach($myarray as $num){
  if($num > $maxnum) $maxnum = $num;
}
echo "The highest value in the array is $maxnum"; 

[Patrick Taylor]

Thanks. I tried it and got this (lots of rows of it - one row for each of the different values in the array):

"Warning: Invalid argument supplied for foreach()" etc, then at the end of all the warnings: "The highest value in the array is 0".

[Chillijam]

Thanks. I tried it and got this (lots of rows of it - one row for each of the different values in the array):

"Warning: Invalid argument supplied for foreach()" etc, then at the end of all the warnings: "The highest value in the array is 0".

Erm... did you spot the deliberate error in my code above? I was trying to itterate through the non-existant array "$myarray" rather than $my_array.

Oops. Sorry about that.

Should have been...

$maxnum = 0;
foreach($my_array as $num){
  if($num > $maxnum) $maxnum = $num;
}
echo "The highest value in the array is $maxnum" 

[sweatje]

I think it would be better just to do

$maxnum = max($my_array); 

Always try to let c do your heavy lifting with arrays.

[Chillijam]

I think it would be better just to do

$maxnum = max($my_array); 

Always try to let c do your heavy lifting with arrays.

I *knew* there would be a built-in function. Thanks for pointing it out.

[Patrick Taylor]

Yes, I spotted the deliberate mistake before I tried your code. $maxnum = max($my_array); doesn't work, because apparently php requires the actual array values separated by commas and spaces, and not just the array variable. So I was thinking of some array function or something that sends the highest value to the end of the array, then trying to pick out that value, so far without success.

[sweatje]

$maxnum = max($my_array); doesn't work, because apparently php requires the actual array values separated by commas and spaces, and not just the array variable.

What you said does not make sence. Can you post the results of

var_dump($my_array); 

I suspect you are working with a string, not an array.

[Patrick Taylor]

echo $my_array; 

produces this:

534527008476254675896872564758968625 etc etc

- it's actually made up of 3-figure numbers.

$maxnum = max($my_array);
echo $maxnum; 

produces a whole set of lines like this:

Warning: Wrong parameter count for max() in /home/username/public_html/folder/filename.php on line 145
string(3) "124" 537

var_dump($my_array); 

produces this:

124string(3) "124" 537string(3) "537" 496string(3) "496" 388string(3) "388" 219string(3) "219" 344string(3) "344" 347string(3) "347" 526string(3) "526"

[sweatje]

It looks to me like you are running var_dump($my_array) in a loop where $my_array is a three character string every time you look at it.

I assume you have $my_array = mysqlblahblah() somewhere. Try doing $my_array[] = mysql... instead.

[Patrick Taylor]

$my_array comes from a query using GROUP BY, which gives a set of results which include a number on each row ($row['2']). It's that number I want the highest one of.

while ($row = mysql_fetch_assoc($result)) {
$my_array = $row['2'];
etc 

When I echo $my_array; outside the loop (still creating it inside the loop) the printout is just one 3-figure number - the last one from the array.

Sorry but I don't understand what you mean by:

$my_array[] = mysql...

[sweatje]

before the loop:

$my_array = array(); 

in the loop:

$my_array[] = $row['2']; 

Alternativly, if you are not going to use $my_array for anything else:
before the loop:

$max_val = 0; 

in the loop:

$max_val = max($max_val, $row[2]); 

[dtang4]

You need to first split the string into an array of 3-digit numbers. I don't know if there's a function to do that, but you can try something like this (code below has not been tested)...

while($my_array > 0) { 
	 $array[] = ($my_array/1000 - floor($my_array/1000)) * 1000;
	 $my_array = floor($my_array/1000);
}
function_call($array);

[Patrick Taylor]

dtang4 - thanks for the suggestion. I have it working after sweatje's last post.

sweatje, your first option produced "wrong parameter count for max()". I was under the impression a single value in the brackets wouldn't work with "max" - don't know - but your second option did the job.

A big "thankyou" from me. Nice work.

Regards,

Patrick

[sweatje]

You need to first split the string into an array of 3-digit numbers. I don't know if there's a function to do that, but you can try something like this (code below has not been tested)...

while($my_array > 0) { 
	 $array[] = ($my_array/1000 - floor($my_array/1000)) * 1000;
	 $my_array = floor($my_array/1000);
}
function_call($array);

This was not his issue, it was not a long string, but rather a short string that he was replacing each time through the loop.

However, if it were a long string, I would have choosen an approach like this rather than your code:

$test = '12345678901';
preg_match_all('/(\d{1,3})/', $test, $matches);
var_dump($matches[1]);
echo max($matches[1]); 

producing:

array(4) {
  [0]=>
  string(3) "123"
  [1]=>
  string(3) "456"
  [2]=>
  string(3) "789"
  [3]=>
  string(2) "01"
}
789

Again, try to let c do the heavy lifting, preg_match_all will be much faster than looping in PHP and calling the floor function repeatedly.

Regards,

Jason

[sweatje]

alternativly, if you do not care for regular expresions:

$my_array = explode("\n",chunk_split($test,3));
var_dump($my_array);
echo max($my_array); 

Not sure which is faster, but both should be faster than looping in php.