php array traversal

/* Array traversal
*
* 1. Use the for statement to loop through the array
* a. Other languages ​​(only this way)
* b. This method in PHP is not our preferred method
*C. The array must be the index array, and the bidding must be continuous
*(the index array is bidding, it can also be discomfort, there is a control array in the array)
*
*
2. Use the FOREACH statement to circulate through the array of arrays through the array of arrays
* foreach (array variable as variable value) {
* //Loop body
* }
* a. The number of loops is determined by the number of elements in the array
* b. Each loop will assign the elements in the array to the following. Variable
*
* foreach (array variable as subscript variable => value variable) {
*
* }
*
* 3. while() list() each() combination loop traverses the array
*
* each( ) function,
*   a. Requires an array as a parameter
*     b. The returned array is also an array
*       c. The returned array is 0, 1, key, value four subscripts (fixed)
*     0 and The key subscript is the key of the current parameter array element
*   1 and the value subscript is the value of the current logarithmic array element
*
* d. By default, the current element is the first element
*       e. After each execution, it will Move the current element backward
*                                                                                                                                                                                ; id [key] => id )
*
* list() function

* a. list()=array(); You need to assign an array to this function
* b. The number of elements in the array, The number of parameters in the list() function must be the same
* c. Each element value in the array will be assigned to each parameter in the list() function, and list() will convert each parameter into a variable
* d. list () can only receive index arrays
* e. In the order of index subscripts
*/
/*
$user=array("id"=>1, "name"=>"zhangsan", "age" =>10, "sex"=>"nan");

while($arr=each($user)){
//echo $arr[0]."==>".$arr[ 1]."
";
echo $arr["key"]."---->".$arr["value"]."
";
}

Use array Internal pointer control function
next(array);
prev(array);
reset(array)
end(array);

current(array);
key(array);
*/