What is the difference between linked list and array in php

In PHP, linked lists and arrays are ways to implement data structures. Although both can be used to store and manipulate data, they have obvious differences in underlying implementation and application scenarios.

An array is a linear structure consisting of a set of elements of the same type, each element has a unique subscript or key value. In PHP, arrays can use indexes or associated keys to access elements. Arrays are often used to store elements with similar attributes or categories, such as city names or product lists. The advantage of arrays is that they can quickly access elements based on keys or indexes, making it easy to query and add data.

In contrast, a linked list is a non-linear structure composed of multiple nodes. Each node contains two parts: a data part and a pointer to the next node. Linked lists have no fixed size and elements can be added or deleted dynamically. The advantage of linked lists is that elements can be added and removed efficiently because elements in a linked list can be manipulated without moving other elements.

When using PHP, you need to choose whether to use an array or a linked list according to actual needs. If you need to perform query and sort operations efficiently, using arrays is more appropriate. If you need to add and delete elements frequently, using a linked list can be more efficient. At the same time, it should be noted that the memory footprint of arrays is larger than that of linked lists, because arrays need to allocate fixed space in advance, while linked lists can automatically adjust as the number of elements changes.

It should be noted that arrays in PHP are actually a mixed structure. In terms of underlying implementation, PHP's arrays can use either hash tables or ordered arrays. When adding a small number of elements, PHP uses an ordered array to ensure query efficiency; when adding a large number of elements, PHP will automatically convert to a hash table to improve adding and query efficiency. Therefore, PHP's arrays have high flexibility and efficiency, and are suitable for most usage scenarios.

When summarizing the above, the following conclusions can be drawn:

1. An array is a linear structure consisting of elements of the same type, each element has a unique subscript Or key value. Suitable for query and sort operations.
2. A linked list is a non-linear structure consisting of multiple nodes, each node contains a pointer to the next node. Suitable for frequent element addition and deletion operations.
3. In PHP, an array is a hybrid structure that can be implemented using an ordered array or a hash table. Flexible and efficient, suitable for most scenarios.

Based on the above differences and adaptation scenarios, developers should flexibly choose to use PHP's array or linked list data structure according to actual application needs. This can make the program more efficient and improve development efficiency.

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