How are associative arrays implemented in PHP?

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The highest voted answer link is broken and doesn’t give that much explanation.

PHP is written in C and the underlying structure is just a C array. C arrays are just chunks of memory. The indexes in C arrays must be continuous, you can’t have an index 0 and an index 1000 that comes after it. To make associative array keys work, before they are added to the C array, they are converted to proper C indices via a hash function.

For a full explanation, I found this link to be much more informative.

http://nikic.github.io/2012/03/28/Understanding-PHPs-internal-array-implementation.html

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