=> and <=

[Zane]

[ot]It's been awhile since I've asked a question in this board.  Just goes to show you that you just can't know it all.[/ot]

 

So I was digging through some code when I came across the

 

What is it's purpose.  I want to say it's a reverse assignment operator but that just make entirely no sense.

 

Just for the clueless ones reading I'll elaborate with code

$someArray = array (
     'keyOne' => "the value",
     'keyTwo' => "the value" );

or this

foreach ($array as $key=> $value )
      while ($key                  $blah -= $key;
                 $str.= $value;
       }

[trq]

Your first example is invalid. Your second says while $key is less than or equal to $blah.

[Zane]

good god I need to go to sleep.  How did I not know that?

[trq]

I have no idea. It is a very common comparison operator.

[oni-kun]

"=>" is a key assignment.  "'keyOne' => "the value"," is like an ARROW. (That's where you were confused)

"<=" is an operator, such as.. < OR =, as in 'LESS or EQUAL TO', note operators are before the equals in this math.

[Mchl]

Your first example is invalid.

 

It's not. It will evaluate to false.

[Zane]

I was reading through the SMF code is where I got it... that probably explains my confusion.  I still feel completely retarded for posting this topic now..

 

is like an ARROW. (That's where you were confused)

Yeah.. that's it.

 

Lesson of the day: Always reread your OP at least 5 more times before ever posting it.

[trq]

Your first example is invalid.

 

It's not. It will evaluate to false.

Ah. It actually evaluates to true. I assume because the string "the value"  is considered to be less than "something else". Strange thing is, if you swap them. ("something else" <= "the value") it evaluates to null (which is of course also considered false).

[salathe]

Ah. It actually evaluates to true. I assume because the string "the value"  is considered to be less than "something else". Strange thing is, if you swap them. ("something else" <= "the value") it evaluates to null (which is of course also considered false).

It actually doesn't, Mchl was right in saying "the value" <= "something else" evaluates to FALSE. If you swap them ("something else" <= "the value"), that evaluates to TRUE. I'm not sure how you arrived at the FALSE and NULL values.

 

[trq]

Ah. It actually evaluates to true. I assume because the string "the value"  is considered to be less than "something else". Strange thing is, if you swap them. ("something else" <= "the value") it evaluates to null (which is of course also considered false).

It actually doesn't, Mchl was right in saying "the value" <= "something else" evaluates to FALSE. If you swap them ("something else" <= "the value"), that evaluates to TRUE. I'm not sure how you arrived at the FALSE and NULL values.

 

 

I was using "a" <= "aa" in my tests. But now, well, its an even weirder result.

 

#!/usr/bin/php
<?php

$a = array(
    1 => 'a' <= 'aa',
    2 => 'aa' <= 'a',
    3 => 'the value' <= 'something else',
    4 => 'something else' <= 'the value'
);

var_dump($a);

 

array(4) {
  [1]=>
  bool(true)
  [2]=>
  bool(false)
  [3]=>
  bool(false)
  [4]=>
  bool(true)
}

[Mchl]

Weirder? Why?

I would think that's pretty common algorithm for string comparison.

[trq]

Weirder? Why?

I would think that's pretty common algorithm for string comparison.

 

What is? I can't see the pattern.

[Mchl]

Something like this

function compareStrings($strA,$strB) {
  $A = false;  //strA is larger
  $B = false;  //strB is larger
  
  $toCompare = max(strlen($strA),strlen($strB))
  
  for ($i = 0; $i < $toCompare, $i++) {  //first compare character-to-character as long as both strings have characters ;P
    if (ord($strA[$i]) > ord($strB[$i]) {
      $A = true;
      break;
    } elseif (ord($strA[$i]) < ord($strB[$i]) {
      $B = true;
      break;
    }
    if (!$A && !$B) {  //if strings were equal to this moment, then the one having more character is 'larger'
      if(strlen($strA) >= strlen($strB)) {
	$A = true;
      }
  if(strlen($strA) <= strlen($strB)) {
	$B = true;
      }
    }

if($A && $B) return 0;
if($A && !$B) return 1;
if(!$A && $B) return -1;
if(!$A && !$B) return 'WTF';  //this should not happen

  }
}

[trq]

Had to fix a few things and changed the return values somewhat.

 

#!/usr/bin/php
<?php
function compareStrings($strA,$strB) {
  $A = false;  //strA is larger
  $B = false;  //strB is larger

  $toCompare = max(strlen($strA),strlen($strB));

  for ($i = 0; $i < $toCompare; $i++) {  //first compare character-to-character as long as both strings have characters ;P
    if (ord($strA[$i]) > ord($strB[$i])) {
      $A = true;
      break;
    } elseif (ord($strA[$i]) < ord($strB[$i])) {
      $B = true;
      break;
    }
    if (!$A && !$B) {  //if strings were equal to this moment, then the one having more character is 'larger'
      if(strlen($strA) >= strlen($strB)) {
      $A = true;
      }
     if(strlen($strA) <= strlen($strB)) {
      $B = true;
      }
    }
   
   if($A && $B) return "false";
   if($A && !$B) return "true";
   if(!$A && $B) return "false";
   if(!$A && !$B) return 'error';  //this should not happen
   
  }
}

 

<?php echo compareStrings('a', 'aa');?> // returns 'false'

<?php echo compareStrings('the value', 'something else');?> // returns nothing at all

[.josh]

@OP: HAHA FAIL (sorry, had to rub it in)

 

 

Weirder? Why?

I would think that's pretty common algorithm for string comparison.

 

 

What is? I can't see the pattern.

 

when you compare one string to another like that, php converts both strings to numbers.

[Mchl]

Had to fix a few things and changed the return values somewhat.

 

I've never even tried to run it, so that explains syntax errors (yes it does, I tell you!)

As for the return values, I made them in accordance to callback used in usort

[Daniel0]

Weirder? Why?

I would think that's pretty common algorithm for string comparison.

 

What is? I can't see the pattern.

 

It's called lexicographical order.