What is the difference between indexed and associative array?

In PHP, indexed arrays and associative arrays are two fundamental data structures used to store collections of data, but they differ in how they organize and access their elements:

1. Indexed Array:
   • Indexed arrays are also known as numeric arrays.
   • Elements in an indexed array are accessed and referenced using numeric indices (starting from 0).
   • Indexed arrays maintain a sequential order of elements based on their numeric indices.
   • Example:
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     $indexedArray = array("apple", "banana", "orange");
echo $indexedArray[0]; // Outputs: apple

2. Associative Array:
   • Associative arrays are also known as key-value pairs or hash maps.
   • Elements in an associative array are accessed and referenced using keys (which can be strings or integers).
   • Associative arrays do not maintain a specific order of elements.
   • Example:
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     $assocArray = array("name" => "John", "age" => 30, "city" => "New York");
echo $assocArray["age"]; // Outputs: 30


Key Differences:

• Access Method: Indexed arrays are accessed using numeric indices, while associative arrays are accessed using keys.
• Ordering: Indexed arrays maintain a specific order based on numeric indices, while associative arrays do not guarantee any particular order.
• Usage: Indexed arrays are suitable for ordered collections where elements have a numerical significance (e.g., arrays of items in a list). Associative arrays are used when you need to associate a key with a value, often to represent attributes or properties of something.

In an interview, it’s beneficial to elaborate on these points and provide examples to demonstrate understanding.