<?php
/* Traversal of arrays
*
* 1. Looping through an array using a For statement
* 1. Other languages (only this one way)
* 2.PHP in this way is not the preferred way
* 3. The array must be an indexed array, and the subscript must be contiguous.
* (index array subscript can be discontinuous, array and associative array, these two cannot traverse)
*
* 2. Looping through an array using a foreach statement
* Foreacho (array variable as variable value) {
*//Circulation body
* }
* 1. The number of cycles is determined by the number of elements in the array
* 2. Each time the loop assigns the elements in the array to the following variables
*
* foreach (array variable as subscript variable => value variable) {
* }
*
*
* 3.while () list () each () combines loop traversal array
*
* each () function:
* 1. Need an array as a parameter
* 2. The return is also an array
* 3. The returned array is 0,1,key,value four subscript (fixed)
* 0 and key subscript are keys to the elements of the current parameter array
* 1 and value subscript are the values of the current parameter array elements
* 4. The default current element is the first element
* 5. The current element is moved backwards after each execution
* 6. Returns False if the function is executed again to the last element
* List () function:
* 1. List () =array (); You need to assign an array to this function
* 2. The number of elements in the array to be the same as the number of parameters in the list () function
* 3. Each element value in the array assigns each parameter in the list () function, and the list () converts each argument to a variable
* 4.list () can only accept indexed arrays
* 5. Assigning values to parameters by index order of subscript
*
*
*
*/
For statement Traversal array
$user =array (1, "Zhangsan", "Nan");
For ($i =0 $i <4; $i + +)
{
echo \ $user [{$i}]=]. $user [$i]. " <br> ";
}
Using foreach
$user =array (1, "Zhangsan", "Nan");
foreach ($user as $val)//$val are custom variables
{
echo $val. " <br> "//output is independent of subscript
}
foreach ($user as $key => $val)//$val $key are custom variables
{
echo $key. " =====> ". $val." <br> ";
}
foreach traverses multidimensional arrays
$info =array (
"User" =>array (
$user [0]
Array (1, "Zansan", Ten, "Nan"),
$user [1][1]
Array (2, "Lisi", "NV"),//$user [1]
$user [2]
Array (3, "Wangwu", "Nan")
),
"Score" =>array (
Array (1, 100, 90, 80),
Array (2, 99, 88, 11),
Array (3, 10, 50, 88)
),
"Connect" =>array (
Array (1, ', ', ' aaa@bbb.com '),
Array (2, ' bbb@ccc.com ', '),
Array (3, ' 119 ', ' ccc@ddd.com ')
)
);
foreach ($info as $tableName => $table)
{
Echo ' <table align= "center" width= "border=" 1 ">";
Echo ' <caption>foreach ($table as $row)
{
Echo ' <tr> ';
foreach ($row as $col)
{
Echo ' <td> '. $col. ' </td> ';
}
Echo ' </tr> ';
}
Echo ' </table> ';
}
Use of each ()
$user =array ("id" =>1, "name" => "Zhangsan", "Age" =>10, "Sex" => "Nan");
$a =each ($user);//array ([1] => 1 [value] => 1 [0] => ID [key] => ID) default is the value of the first element
Print_r ($a);
$b =each ($user);
Print_r ($b);//array ([1] => Zhangsan [value] => Zhangsan [0] => name [key] => name) iterate backward through one of each execution
$c =each ($user);
Print_r ($c);//array ([1] => [value] => [0] => age [key] => age)
$d =each ($user);
Print_r ($d);//array ([1] => nan [value] => nan [0] => sex [key] => sex)
$e =each ($user);
Var_dump ($e);//bool (false) the value returned when there is no element
Each () with the while traversal
$user =array ("id" =>1, "name" => "Zhangsan", "Age" =>10, "Sex" => "Nan");
while ($arr =each ($user))
{
echo $arr [0]. " ====> ". $arr [1]." <br> "//pass 0 to show key (subscript) and value
echo $arr ["Key"]. " ===> ". $arr [" Value "]." <br>//By Key,value to display the key value
}
Use of the list () function
List ($name, $age, $sex) =array ("Zhangsan", "nnnnn");
echo $name. " <br> ";
echo $age. " <br> ";
echo $sex. " <br> ";
Another way to use
List (,, $sex) =array ("Zhangsan", "nnnnn");
echo $sex. " <br> "//Only convert sex to variable
IP judgment
$ip = "192.168.1.128";
List (,,, $d) =explode (".", $ip);//explode. To separate and return an array of
echo $d//Remove 128
List () can only receive examples of indexed arrays
$user =array ("id" =>1, "name" => "Zhangsan", "Age" =>10, "Sex" => "Nan");
List ($key, $value) =each ($user);//array ([1]=>1 [0]=>id) Assign values to the parameters in the list in the order of the index subscript, so first 0 keys and then 1 values
echo $key. " ---> ". $value;
The while list () is combined with the
$user =array ("id" =>1, "name" => "Zhangsan", "Age" =>10, "Sex" => "Nan");
while (list ($key, $value) =each ($user))
{
echo $key. " ---> ". $value." <br> ";
}
Multiple loops show only one solution at a time
Using an array's internal pointer control function
Next (array); The array pointer moves to the next
Prev (array); array pointer moves to previous
Reset (array); The array pointer moves to the first (reset)
End (array); The array pointer moves to the last
Current (array); Gets the value of the present element, the element to which the exponential group pointer points when the current element is present.
Key (array); Get the value of the current element (subscript)
$user =array ("id" =>1, "name" => "Zhangsan", "Age" =>10, "Sex" => "Nan");
while (list ($key, $value) =each ($user))
{
echo $key. " ---> ". $value." <br> ";
}
Here, move the array pointer to the first loop below to output
Reset ($user)
while ($key, $value) =each ($user))//Because each () returns false to the last, the loop jumps directly
{
echo $key. " ---> ". $value." <br> ";
}
while ($key, $value) =each ($user))//Because each () returns false to the last, the loop jumps directly
{
echo $key. " ---> ". $value." <br> ";
}
Echo current ($user). =====> ". Key ($user);
?>
