有趣的javascript数组定义方法_基础知识
var Person = new Array();
Person[0] = 120;//定义人的体重 120斤
Person[1] = 21;//定义人的年龄 21岁
document.write(“体重="+Person[0]+"年龄="+Person[1]);//输出人的体重和年龄
另一个有趣的定义数组的方法:
var Person = new Array();
Person["weight"] = 50;
Person["age"] = 40;
document.write("体重="+Person["weight"]+"年龄="+Person["age"]);
以上这种方法称为 “关联数组”,是通过一个特定的值来索引数组的。实际上数值数组可以被当作关联数组的一种特例来对待。
用关联数组来代替数值数组的做法意味着,我们可以通过各元素的名字而不是一个下标数字来引用它们,这样大大提高了脚本的可读性。

Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics











The method of using a foreach loop to remove duplicate elements from a PHP array is as follows: traverse the array, and if the element already exists and the current position is not the first occurrence, delete it. For example, if there are duplicate records in the database query results, you can use this method to remove them and obtain results without duplicate records.

Methods for deep copying arrays in PHP include: JSON encoding and decoding using json_decode and json_encode. Use array_map and clone to make deep copies of keys and values. Use serialize and unserialize for serialization and deserialization.

The performance comparison of PHP array key value flipping methods shows that the array_flip() function performs better than the for loop in large arrays (more than 1 million elements) and takes less time. The for loop method of manually flipping key values takes a relatively long time.

Multidimensional array sorting can be divided into single column sorting and nested sorting. Single column sorting can use the array_multisort() function to sort by columns; nested sorting requires a recursive function to traverse the array and sort it. Practical cases include sorting by product name and compound sorting by sales volume and price.

PHP's array_group_by function can group elements in an array based on keys or closure functions, returning an associative array where the key is the group name and the value is an array of elements belonging to the group.

The best practice for performing an array deep copy in PHP is to use json_decode(json_encode($arr)) to convert the array to a JSON string and then convert it back to an array. Use unserialize(serialize($arr)) to serialize the array to a string and then deserialize it to a new array. Use the RecursiveIteratorIterator to recursively traverse multidimensional arrays.

Complexity of PHP array deduplication algorithm: array_unique(): O(n) array_flip()+array_keys(): O(n) foreach loop: O(n^2)

PHP's array_group() function can be used to group an array by a specified key to find duplicate elements. This function works through the following steps: Use key_callback to specify the grouping key. Optionally use value_callback to determine grouping values. Count grouped elements and identify duplicates. Therefore, the array_group() function is very useful for finding and processing duplicate elements.
