PHP array pointer operation implementation code_PHP tutorial

/**
* Back the internal pointer of the array by one bit
* @param array &$arr
* @return mixed Returns the value of the previous unit, and returns FALSE when there are no more units
* if If the array contains empty cells, or the value of the cell is 0, this function will also return FALSE when encountering these cells
* To correctly traverse the array that may contain empty cells or the value of the cell is 0, see each() function
*/
mixed prev(array &$arr);
$transport = array('foot', 'bike', 'car', 'plane' );
$mode = current($transport); // $mode = 'foot';
$mode = next($transport); // $mode = 'bike';
$mode = next($transport); // $mode = 'car';
$mode = prev($transport); // $mode = 'bike';
$mode = end($transport); // $mode = 'plane';
$mode = reset($transport) ;//$mode = 'foot';
?>

array("key"=>"value ");Create an array
//Display the array
print_r($array);
//Use the compact() function to create a new array and use the parameters as the units of the new array;
$newArray = compact("red","green","yellow","blue","array");
//Use the extract() function to convert the cells in the array into variables
extract($exArray);
echo "$key1 $key2 $key3 $key4 $key5";


※Check value, key
array_key_exists($key,$array);//Check array key
in_array($value,$array);//Check the value in the array

※Get the value
//Use array_values() to get the value of the array
$carValues ​​= array_values($car);
//Get the key name of the array
$twoKeys = array_keys($two);
key($array);//Output the key name of the current unit
//After the array is defined, use current () Get the value of the current unit
$red = current($array);
list($red,$green) = $array;//Assign the value in the array to the variable, $array = array( "Red", "Green");
each($two);//Return the key and value of the current unit in the array

※Traverse the array
foreach($two as $subArray); //Traverse the array
while(list($key,$value) = each($array)){
echo "$key=>$value,";//Use each to traverse the array
}

※Fill the array
//Fill the array to the left and right
array_pad($array,+3,"shuzhi");//The 2nd parameter is filled from left to right, the value is greater than Only fill in the number of cells
$array1 = array_fill(5,5,"test");//Use array_fill() to fill the value of this array, the value is test, start filling from the 5th cell, and fill 5 in total Unit
//Fill array key name
$keys = array('string', 5, 10, 'str');
$array3 = array_fill_keys($keys, "array value");
//Use the array_filp() function to exchange key names and values
$speed = array_flip($speed);
//Use the array_splice() function to replace the value of the 6th unit with 7
$output = array_splice($input,6,0,7);
//Use the array_splice() function to delete the array cells and keep only the first 5 cells
$output = array_splice($input,5);
$ array1 = range(10,100,10); //Use the third parameter of the range() function to set the step value between units


※Sort
shuffle($array); //Shuffle the order of the arrays
//Use array_multisort() to sort three arrays
array_multisort($sort1,$sort2,$sort3);
//Sort this array and keep the index Relationship
asort($array);
//Reverse sort the test array and maintain the index relationship
arsort($array);
//Use ksort() to sort the array by key name
ksort($array);
//Use krsort() function to reverse sort by key name
krsort($array);
//Use sort() to sort the test array [arranged by key name] ]
sort($array);
//Use natsort() to sort [natural sorting, numerical arrangement] sensitive to the case of unit values ​​
natsort($array);
//Use natcasesort ()Function sorting [natural sorting] but ignoring numerical case
natcasesort($array);
//Use the array_reverse() function to sort, and the array units are arranged in reverse order
$newArray = array_reverse($array, TRUE);//Retain the original key name when TRUE is set

※Intersection and difference set
//Use array_diff() to calculate the difference set of three arrays [Compare array values]
$result = array_diff($dog1,$dog2,$dog3);
//Use array_diff_assoc() to calculate the difference set of three arrays [compare values ​​and key names]
$result = array_diff_assoc($dog1,$dog2 ,$dog3);
//Use array_diff_key() to calculate the difference set of three arrays [compare key names]
$result = array_diff_key($dog1,$dog2,$dog3);
//Use array_intersect() calculates the intersection of three arrays [compare array values]
$result = array_intersect($dog1,$dog2,$dog3);
//Use array_intersect_assoc() to calculate the intersection of three arrays [compare array values] Comparison of values ​​and key names]
$result = array_intersect_assoc($dog1,$dog2,$dog3);
//Use array_intersect_key() to calculate the intersection of three arrays [Compare key names]
$result = array_intersect_key($dog1,$dog2,$dog3);

※Merge arrays
//Use array_merge() function to merge arrays
$result = array_merge($array1,$array2,$array3, $array4,$array5);
array_rand($input,10);//Randomly take out 10 units
count($array,COUNT_RECURSIVE);//Display the number of array units, parameter 2 can only be 1 or COUNT_RECURSIVE, sometimes you can traverse multi-dimensional arrays

※Pop and pop
//Array pops from the stack, last in first out, the last unit of the array pops up
array_pop($array);
//Array in Stack, add two values ​​​​7 and 8 to the end of the array
array_push($array, 7, 8);
//Move the beginning unit of the array out of the array
array_shift($array);
/ /Add 7, 8 to the beginning of the array
array_unshift($array,7,8);

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