Consider I have associative array with same key values:
$arr = {'MessageID' =>1 ,'MessageID' =>5 , 'MessageID' => 8};
Now I want every call to function foo() which will insert a new key value of 'MessageID'=>integer
How can we do that without overriding other existing key values pairs?
As many answerers before, you can't have keys with the same string in the array in PHP. If you want to represent multiple values per key I use something like this:
$arr = ['MessageID' => [1, 5, 8]];
You would append to MessageID with this code:
$arr['MessageId'][] = 10;
Then it would look like this:
['MessageID' => [1, 5, 8, 10]]
This worked well for me with HTTP headers and other things which are key value based, but can have multiple values.
In php array, you can not insert multiple values with same index. If you want to use it then you can use it with following manner
$MessageID = array(1,5,8);
and
$MessageID[] = $newValue; to insert new value.
You cannot have an array with duplicate keys.
A better implementation would be to have an array called $messageIDs and save the actual values in the array:
$messageIDs = array (1, 5, 8);
As i mentioned in comments, you cannot have duplicate keys in an array. Also your sample with curly braces is not valid php syntax.
Perhaps you need a multidimentional array:
$arr = [['messageID'=>1],['messageID'=>5],['messageID'=>8]];
in which case you would add another value like so:
$arr[] = ['messageID'=>11];
