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(100,200,3 00);

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]); } 
      }