Summary of PHP array traversal statements (foreach, for, list, each)_PHP tutorial

When using foreach to access, is the order of traversal fixed? In what order should it be traversed?

For example:

The code is as follows

$colors= array('red','blue','green','yellow');
foreach ($colors as $color){
//add your codes
}
?>

Example 2

$capitals= array("Ohio"=> "Columbus","Towa"=> "Des Moines","Arizona"=> "Phoenix");
foreach($capitals as $key=> $val){
//add your codes
}

while()

while() is usually used in conjunction with list() and each().

#example2:

The code is as follows

$colors = array('red','blue','green','yellow');

while(list($key,$val) = each($colors)) {
echo "Other list of $val.
";
}
?>

Display results:

Other list of red.
Other list of blue.
Other list of green.
Other list of yellow.

3. for()
#example3:

The code is as follows

$arr = array ("0" => "zero","1" => "one","2" => "two");

for ($i = 0;$i < count($arr); $i++) {
$str = $arr[$i];
echo "the number is $str.
";
}
?>
Display results:

the number is zero.
the number is one.
the number is two.

========= The following is the function introduction ==========

key()
mixed key(array input_array)

The key() function returns the key element in input_array at the current pointer position.

#example4

The code is as follows

$capitals = array("Ohio" => "Columbus","Towa" => "Des Moines","Arizona" => "Phoenix");
echo "

Can you name the capitals of these states?

";
while($key = key($capitals)) {
echo $key."
";
next($capitals);
//Each key() call does not advance the pointer. To do this, use the next() function
}
?>

Can you name the capitals of these states?
Ohio
Towa
Arizona

each() function traverses the array

Example 1

The code is as follows

$people = array("Peter", "Joe", "Glenn", "Cleveland");
print_r (each($people));
?>

Output:

Array ( [1] => Peter [value] => Peter [0] => 0 [key] => 0 )

Son 2
each() is often used in conjunction with list() to iterate over an array. This example is similar to the previous example, but the entire array is output in a loop:

The code is as follows

Copy code

$people = array("Peter", "Joe", "Glenn", "Cleveland");

reset($people);

while (list($key, $val) = each($people))
{
echo "$key => $val
";
}
?>

Output:

0 => Peter
1 => Joe
2 => Glenn
3 => Cleveland

Recursive traversal of multidimensional arrays

The code is as follows

/*
*------------------------------------------------
*Author:
* Url : www.45it.com* Date : 2011-03-09
*------------------------------------------------
*/
function arr_foreach ($arr)
{
if (!is_array ($arr))
{
return false;
}

foreach ($arr as $key => $val )
{
if (is_array ($val))
{
arr_foreach ($val);
}
else
{
echo $val.'
';
}
}
}

$arr1 = array (1=>array(11,12,13,14=>array(141,142)),2,3,4,5);

echo '

';

print_r($arr1);

echo '
';

arr_foreach ($arr1);

?>
Results
Array

(

[1] => Array

(

[0] => 11

[1] => 12

[2] => 13

[14] => Array

(

[0] => 141

[1] => 142

)
)
[2] => 2

[3] => 3

[4] => 4

[5] => 5

)

11

12

13

141

142

2

3

4

5
 


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