<?php
/*
* 1. Overview of arrays
* 1. The nature of arrays: management and operations 1 Set of variables , Batch processing
* 2. Array is a compound type ( You can store multiple )
* 3. Arrays can store data of any length or type
* 4. Arrays perform the functions of data structures in other languages ( Linked list, queue, stack, collection class )
*
*
*
* 2. Classification of arrays
* There are multiple cells in the array, ( Units are called elements.)
* Each element ( The subscript [ key ] And the value )
* When a single element is accessed, the index is used ( key ) To access elements
* 1.1 Dimensional array, 2 Dimensional array, 3 Dimensional array... Multidimensional array
* ( An array of arrays is an array in which there are other arrays )
* 2.PHP There are two types of arrays
* Indexed array: an index whose index index is a sequence of integers
* Associative array: the index is a string
*
* The subscript ( Integer, string ) There are only two
*
*
* 3. Arrays are declared in many ways
*
* 1. Directly assign a value declaration to an array element
* If the index index is not given, the 0 Start order index
* If I give you the index index, down 1 I'm going to start with the largest 1
* If the preceding subscript appears, if it's an assignment, it reassigns the preceding element
* When mixing declarations, indexes and associations do not affect each other ( Does not affect the index index declaration )
*
* 2. use array() Function declaration
* The default is an indexed array
* If you specify subscripts for associative and indexed arrays, use key => value
* Used between multiple members " , " segmentation
* 3. Use other function declarations
*
*
*
*
*/
// The index array
$user[0]=1;// User number
$user[1]="zhangsan";// The user name
$user[2]=10;// age
$user[3]="nan";// gender
echo '<pre>';
print_r($user);
echo '</pre>';
// An associative array
$user["id"]=1;
$user["name"]="zhangsan";
$user["age"]=10;
$user["sex"];
$user["age"]=90;// The assignment
echo $user["name"];// The output
// use array() Declare an array
$user=array(1,"zhangsan",10,"nan");
// use array() Declare associative array
$user=array("id"=>1,"name"=>"zhangsan","age"=>10,"sex"=>"nan");
// Declare multidimensional array ( Multiple records ) To save 1 Multiple records of user information in table
$user=array(
// with $user[0] Call it 1 Line, such as calling the name in this record ,$user[0][1]
array(1,"zhangsan",10,"nan"),
// with $user[1] Call it 1 Line, such as calling the name in this record ,$user[1][1]
array(2,"lisi",20,"nv")
);
// An array holds multiple tables, each with multiple records
$info=array(
"user"=>array(
array(1,"zhangsan",10,"nan"),
array(2,"lisi",20,"nv")
),
"score"=>array(
array(1,90,80,70),
array(2,60,40,70)
)
);
echo $info["score"][1][1];// The output 60,
?>