If you are looking for a way to count the total number of times a specific value appears in array, use this function: Therefore, the information about which books are checked out to which patrons may be represented by an associative array, in which the books are the keys and the patrons are the values. extract all values from a multi dimesnsional array or a nexted json object Other functions below create a one-dimensional array preserving the last key. Note that in a multidimensional array, each element may be identified by a _sequence_ of keys, i.e. A comment on array_merge mentioned that array_splice is faster than array_merge for inserting values. For completeness, I will add a function that merges the key sequence by a given separator and a function that preserves the last n keys, where n is arbitrary. This may be the case, but if your goal is instead to reindex a numeric array, array_values() is the function of choice. Remember, that the following way of fetching data from a mySql-Table will do exactly the thing as carl described before: An array, which data may be accessed both by numerical and DB-ID-based Indexes: Most of the array_flatten functions don't allow preservation of keys. I needed a function that recursively went into each level of the array to order (only the indexed) arrays... and NOT flatten the whole thing. Associative arrays are used to store key value pairs. For dictionaries with very small numbers of mappings, it may make sense to implement the dictionary using an Another very simple implementation technique, usable when the keys are restricted to a narrow range, is direct addressing into an array: the value for a given key The two major approaches to implementing dictionaries are a The most frequently used general purpose implementation of an associative array is with a Another common approach is to implement an associative array with a Compared to hash tables, these structures have both advantages and weaknesses. The worst-case performance of self-balancing binary search trees is significantly better than that of a hash table, with a time complexity in It is worth noting that a self-balancing binary search tree can be used to implement the buckets for a hash table that uses separate chaining. same array_flatten function, compressed and preserving keys.

For example, to store the marks of different subject of a student in an array, a numerically indexed array would not be the best choice. Useful.

In this case, I can make the function return an array from id to [array of values], and by a simple call to array_values() this is transformed into an array indexed from 0 to count()-1. Just a warning that re-indexing an array by array_values() may cause you to reach the memory limit unexpectly. Each book in a library may be checked out only by a single library patron at a time. This is another way to get value from a multidimensional array, but for versions of php >= 5.3.x// array(2) { [0]=> string(6) "carrot" [1]=> string(7) "carrot2" }

Good function, if you want to acces associative array element by position: In case you want to replace all keys in multiarrays by integers starting at 0, the following function might help. If John returns his book, that would cause a deletion operation, and if Pat checks out a book, that would cause an insertion operation, leading to a different state: Associative arrays are single-dimensional, unbounded, … The function here flatterns an entire array and was not the behaviour I expected from a function of this name. In an associative array, the association between a key and a value is often known as a "mapping", and the same word mapping may also be used to refer to the process of creating a new association. There are two senses of an ordered dictionary: Here's the fixed version:

A modification of wellandpower at hotmail.com's function to perform array_values recursively. Many programming languages include associative arrays as Associative arrays have many applications including such fundamental The operations that are usually defined for an associative array are:Often then instead of add or reassign there is a single In addition, associative arrays may also include other operations such as determining the number of mappings or constructing an Suppose that the set of loans made by a library is represented in a data structure.

It is not to be confused with "Associative container" redirects here. To guarantee a fixed order of enumeration, ordered versions of the associative array are often used. Ivan's function for example creates a two-dimensional array preserving the last two keys. The latter sense of ordered dictionaries are more commonly encountered.
the keys that lead towards that element. Performing the following functions in a 100,000-iteration loop gave me the following times: ($b is a 3-element array)

In some languages, they are not only built into the standard system, but have special syntax, often using array-like subscripting.