Compare array value with string

[toadstool]

I have an array containing the various products
$inventory = array();
$inventory[0] = "whatever1";
etc
I have an array containing various values
$quantity = array(100,200,300);

I call in a value from a form $_POST[itemname]; say
I assign a variable
$var1="$_POST[itemname]";

I want to compare the input value with the array value e.g.
for($i = 0;$i<$inventory_total;$i++) {
if($inventory[$i] == $item) { code }
}
However, this is always negative as I believe I cannot compare an array item with a string.
The only thing I've found so far is the "mplode" statement
But I want to compare individual array items not a string composed of all of them.
Can anyone suggest a simple conversion so that I can compare values?

[prabirchoudhury]

hey

I want to compare the input value with the array value e.g.
for($i = 0;$i<$inventory_total;$i++) {
if($inventory[$i] == $item) { code }
}

1. if you are checking $item value existing in $inventory array (if i am right) then you would use

 
if (in_array($item, $inventory)) {code}
 

:)

[toadstool]

I'm comparing the value in a form with the contents of an array of text items
If (the array item $inventory) equals the form item ($item1))
then {change/update the value in the $quantity array}
e.g.
for($i = 0;$i<$inventory_total;$i++) {
if($inventory[i] == $item) {
$quantity[$i]=($quantity[$i] + $value); }
}

when I put if($inventory[$i] ==$item) then the answer is false;
when I put if($inventory[$i] = $item) then all values in the array $quantity are updated
,

[code green]

prabirchoudhury is correct.
There is no need to loop through the array 'by hand'. in_array() does that for you.
There is also no need for the quotes

$var1="$_POST[itemname]";

And there should be no problem comparing strings with array elements.
I would qualify your $_POST variables before using them.
By that I mean use trim() and strip_tags() and empty() and isset() and possibly is_string() and is_numeric().

[code green]

Oh yes.If using in_array you will also need to ensure the 'case' matches.
Do this using strtolower() or strtoupper()

[Markus]

And you should be using quotes around your array indeces.

// Good.
$array['index'];
 
// Also good, but will use extra memory.
$array["index"];
 
// Not good. Very bad.
$array[index];
 

[toadstool]

Thank you everyone for your input. You have given me a lot to think about.
I apologize for not indicating this was php.
I have considered the if (in_array($item, $inventory)) {code} suggested by many of you, but I am not sure how I would then update the related $quantity[i] for the item thus found.
If $inventory[i] = $item[i] then I want to update (add to) $quantity[i]
If I use in_array, I can determine that it is in the array, but how do I identify the specific item?

[Markus]

You will want array_search() then; it will return the key of the matched item.

[dlite922]

a common mistake when using array_search(). If your item is the first element, index 0, then the if statement will treat it as false. You need a strict (type) comparison:

$indexFound = array_search($item,$inventory); 
if($indexFound !== false) {
   $itemLookingFor = $inventory[$indexFound]; 
}
 

=== and !== compare the variable type as well. (bool/string/etc)

Hope that helps,




Dan

[toadstool]

Looks good, I'll try it out, I am trying an alternative approach using a class to update the value, but haven't yet managed to increment the value e.g. if further entries are made.

function add_to_cart($product_name, $product_qty) 
     { $this->items[$product_name]=$product_qty; }
       //$_COOKIE[product_name]=$_COOKIE[product_name]+$product_qty} 
 
     function update_cart($product_name, $product_qty) 
      { if( array_key_exists($product_name, $this->items) ) 
        { if( $this->items[$product_name]>$product_qty ) 
            { $this->items[$product_name]-=($this->items[$product_name]-$product_qty); 
}
 
          if( $this->items[product_name]<$product_qty ) 
            { $this->items[$product_name]+=abs($this->items[$product_name]-$product_qty); } 
 
          if($qty==0) 
            { unset($this->items[product_name]); } 
        } 
      } 
 
      function remove_from_cart($product_name) 
      { 
       if( array_key_exists($product_name, $this->items) ) 
         { unset($this->items[$product_name]); } 
      } 
 

[toadstool]

I can get a value here, but I want to increment the value if further entries are made, which would require storing the value. I initially approached it from the idea of updating an array of values.
Still learning how to manage these functions.

[toadstool]

Hi there,
I tried this

$indexFound = array_search($item,$inventory);  
  if($indexFound !== false) { 
  $itemLookingFor = $inventory[$indexFound]; 
  echo "<p> $itemLookingFor= ".$itemLookingFor."</p>";  
  echo "<p> $inventory[$indexFound]= ".$inventory[$indexFound]."</p>";
  }
  else
  { echo "<p> THIS DOESN'T WORK </p>";
  }
 
should I say what message came up?
Too bad, I do appreciate all the comments.  I'm learning a lot here
 

[toadstool]

When one considers the problem
I have a value and some input from a form
I want to add that input to the original value and store it so that I can add further values.
One wouldn't think that would be difficult.

[dlite922]

which message came up? It depends. was your string in the array? if so, you'll see the value twice, if not it will yell at you for not working.

:)

Your welcome anytime,

Dan


EDIT: make that three times because your first echo uses double quotes, which parses that $itemLookingFor variable before the equal sign :P

[toadstool]

In answer to your questions. The item was in the array.
I just rechecked.
And the value didn't come up at all the other one did.
Which is a shame, because everyone seems to be trying to help.

[toadstool]

Well
Anyone that resolves the problem of adding and updating these values ought to get bonus points because despite seeming a relatively simple problem, seems to be just out of reach.
Thanks everyone for your input, it has been interesting so far.

[limweizhong]

The first statement (I believe) cannot work:

$var1="$_POST[itemname]";

... just remove the quotes and add a $ before the itemname

[toadstool]

Actually, I had no problem bringing in the form value.
But getting the $value to work, was more difficult. Sometimes it failed even though the code was unchanged.
Adding to previous totals and retaining the new value evaded me,even with cookies the result was unstable.