PHP associated array usage tips, _ PHP Tutorial

PHP associated array usage skills that everyone should master ,. You should master the PHP associated array usage skills. during PHP development, you will need to create many similar variables either early or late, at this time, you can use the PHP associated array skills that everyone should master as data,

During PHP development, you need to create many similar variables early or late. at this time, you can store data as elements in the array. All elements in the array have their own IDs, so they can be easily accessed.
Join array
Join array. each ID key is associated with a value. It is not the best practice to use a numeric array to store data related to specific named values. By associating arrays, we can use values as keys and assign values to them.
Here we will introduce 10 PHP-related array operations and use them to help you improve development efficiency.
1. add array elements
PHP is a weak type language, which means you do not need to declare an array and its size. On the contrary, you can declare and fill the array at the same time.

$capitals = array(  'Alabama' => 'Montgomery',  'Alaska' => 'Juneau',  'Arizona' => 'Phoenix' ); 

The additional array elements can be appended as follows:

$capitals['Arkansas'] = 'Little Rock'; 

If you are processing a numeric index array, you may want to use the frontend and append elements of the display naming function, such as the array_push () and array_unshift () functions, but these functions cannot operate the associated array.
2. delete array elements
To delete an element from an array, use the unset () function, for example:

unset($capitals['California']); 

When using a numeric index array, there are more ways to delete array elements. you can use the array_shift () and array_pop () functions to delete an element from the beginning and end of the array.
3. exchange keys and values
Suppose you want to create a new array named $ states, use the state government as the index, and use the state name as the associated value. The array_flip () function can easily complete this task.

$capitals = array(  'Alabama' => 'Montgomery',  'Alaska' => 'Juneau',  'Arizona' => 'Phoenix' ); $states = array_flip($capitals); // $states = array( // 'Montgomery' => string 'Alabama', // 'Juneau'   => string 'Alaska', // 'Phoenix'  => string 'Arizona' // ); 

4. Merge arrays
If the preceding array is used by a Web-based "FlashCard" service, you can use array_merge () to test students' knowledge about the state capitals in the United States () functions merge arrays containing states and capitals.

$stateCapitals = array(  'Alabama' => 'Montgomery',  'Alaska' => 'Juneau',  'Arizona' => 'Phoenix' ); $countryCapitals = array (  'Australia' => 'Canberra',  'Austria'  => 'Vienna',  'Algeria'  => 'Algiers' ); $capitals = array_merge($stateCapitals, $countryCapitals); 

5. edit the array value
If the data in the array contains case-insensitive errors, you can use the array_map () function to apply a callback to each array element before inserting the data into the database.

function capitalize($element) {  $element = strtolower($element);  return ucwords($element); } $capitals = array(  'Alabama' => 'montGoMEry',  'Alaska' => 'Juneau',  'Arizona' => 'phoeniX' ); $capitals = array_map("capitalize", $capitals); 

6. sort arrays by pressing the buttons
The flash card program uses various sorting methods. for example, you can use the ksort () function to sort the associated arrays in alphabetical order.

$capitals = array(  'Arizona' => 'Phoenix',  'Alaska' => 'Juneau',  'Alabama' => 'Montgomery' ); ksort($capitals); 

Because the array is passed to The ksort () function through parameters, it means that you no longer need to assign the sorting result to another variable.
7. Random array sorting
Another random sorting technique is involved in the flash card program. in this case, you need to use the shuffle () function to implement random sorting of array projects.

$capitals = array(  'Arizona' => 'Phoenix',  'Alaska' => 'Juneau',  'Alabama' => 'Montgomery' ); shuffle($capitals); 

If you do not need to disrupt the array order and want to randomly select a value, use the array_rand () function.
8. check whether the key and value exist.
You can use the in_array () function to determine whether an array element exists.

$capitals = array(  'Arizona' => 'Phoenix',  'Alaska' => 'Juneau',  'Alabama' => 'Montgomery' ); if (in_array("Juneau", $capitals)) {  echo "Exists!"; } else {  echo "Does not exist!"; } 

Few people know that this function can also determine whether an array key exists. at this point, it functions the same as the array_key_exists () function.

$capitals = array(  'Arizona' => 'Phoenix',  'Alaska' => 'Juneau',  'Alabama' => 'Montgomery' ); if (array_key_exists("Alaska", $capitals)) {  echo "Key exists!"; } else {  echo "Key does not exist!"; } 

9. search for arrays
You may want to search for array resources, so that you can easily search associated states using a specific state government. you can use the array_search () function to search for arrays.

$capitals = array(  'Arizona' => 'Phoenix',  'Alaska' => 'Juneau',  'Alabama' => 'Montgomery' ); $state = array_search('Juneau', $capitals); // $state = 'Alaska' 

10. Standard PHP library
The Standard PHP Library (SPL) provides developers with many data structures, iterators, interfaces, exceptions, and other functions not available in the previous PHP language, these functions can be used to traverse arrays through object-oriented syntax.

$capitals = array(  'Arizona' => 'Phoenix',  'Alaska' => 'Juneau',  'Alabama' => 'Montgomery' ); $arrayObject = new ArrayObject($capitals); foreach ($arrayObject as $state => $capital) {  printf("The capital of %s is %s
", $state, $capital); } // The capital of Arizona is Phoenix // The capital of Alaska is Juneau // The capital of Alabama is Montgomery 

The above are 10 PHP associated array usage skills that must be mastered, and hope to help you learn.

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• 10 PHP operations for associating arrays
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• In php, how do I search for the associated array key value and obtain it?
• PHP combines two joined arrays to improve function efficiency
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• Php uses the array_merge () function to merge correlated and non-correlated arrays.
• PHP converts an object to an associated array for code sharing
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• PHP concatenates arrays to delete elements based on element values

When using PHP for development, you may need to create many similar variables early or late. at this time, you can make the data...