<?php
/**
** 1 Overview of arrays
1. The nature of arrays: management and manipulation 1 Group variables, batch processing
2. An array is a compound type
3. You can store data of any length in an array. You can also store any type of data
4. Arrays perform the functions of data structures in other languages (linked lists, queues, stacks, collection classes)
**
2. Classification of arrays
 There are multiple units in an array (units are called elements)
 Each element is composed of subscripts [keys] and values
 When accessing elements individually, they are all accessed by subscript [key]
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: the index where the subscript [key] is a sequence of integers
 An associative array   : the subscript is the string as the index
 There are only two subscripts (integers, strings)
*
3 . Arrays are declared in many ways
1 Assign values directly to the array elements
 If the index index is not given, it will be given from 0 Starting index
 If you give me the index index 1 I'm going to start with the largest 1
 If there's a subscript in front of it, if it's an assignment, it's a re-assignment of the previous element
d The time index and association of the mixed declaration do not affect each other ( Does not affect the declaration of index subscripts )
2 use array() function

a The default is an indexed array
b . If you subscript associative and indexed arrays, use keys => value
c Use ", "to split between multiple members;
3 Use other function declarations
file();

*
*
*
*
**/

echo $arr[5]

// The index array
$user[]=1;
$user[9]=" zhang 3"
$user[0]=10;
$user[3]="nan";
$info=array(
"$user"=array(
//$user[0]
array("1"," zhang 3",10,"nan"),
//$user[1]
array("2","lisi",10,"nan"),
//$user[2]
array("3","wangwu",10,"nan"),
),
"$score"=array(
//$user[0]
array("1"," zhang 3",10,"nan"),
//$user[1]
array("2","lisi",10,"nan"),
//$user[2]
array("3","wangwu",10,"nan"),
),

"$connect"=array(
//$user[0]
array("1"," zhang 3",10,"nan"),
//$user[1]
array("2","lisi",10,"nan"),
//$user[2]
array("3","wangwu",10,"nan"),
),
};

$user[][]=1;
$user[][]=1;
$user[][]=1;
$user[][]=1;
$user[][]=1;

?>