Detailed explanation of tutorials based on PHP array

Detailed explanation of tutorials based on PHP array_PHP tutorial

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Release： 2016-07-21 15:09:20

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Definition of array
An array is an ordered set of variables, where each variable is called an element.
1. Define the array
You can use the array() language structure to create a new array. It accepts a number of comma-separated key => value parameter pairs.
array( [key =>] value , ... ) // key can be a number or a string // value can be any value
Example 1:

Copy code The code is as follows:

$phpjc = array( 
=>'word', 
=>' excel', 
'outlook', 
'access'); 
print_r($phpjc); 
?>

The output results are as follows:

Copy code The code is as follows:

Array ( [0] => word [3] => excel [4] => outlook [5] => access )

Example 1 defines an array named phpjc, and the value of the first element is: word, (Explanation: The array is Counting from 0), the second element is empty, the third element is: excel, and the fourth and fifth elements are automatically generated later

You can assign an array() without parameters to the variable to create an empty array, then values can be added by using square brackets [] syntax. (Note: You can also use the array_push() function to add values to the array!!!)
Example 2:

Copy Code The code is as follows:

$phpjc = array(); 
$phpjc[] = "one"; 
$phpjc [] = "two"; 
echo $phpjc[0]."
"; 
echo $phpjc[1]; 
?>

The output result is as follows:

Copy the code The code is as follows:

one 
two 

2. Read array elements
Use string index (or key) to access the value stored in the array
Example 3 :

Copy code The code is as follows:

$phpjc = array("first "=>1,"second"=>2,"third"=>3); 
echo $phpjc["second"]; 
$phpjc["third"]=5; // Change the value of the third element from "3" to "5" 
echo $phpjc["third"]; 
?>

There are many array-related things in PHP Functions, one by one, are_array(), n_array(), count(), array_push(), array_unshift(), array_merge(), array_pop(), array_shift(), sort()
1 .is_array() function
is an array
--------------------------------- --------------------------
2.in_array() function
If you have a large An array, and all you want to accomplish is to find the existence of a given value, you can use in_array() to return true or false. The following code will output "Not found in this array" - because you will be looking for an "Alber" in $namesArray that does not exist.

Copy code The code is as follows:

　$namesArray = array("Joe", "Jane ", "Bob", "Mary", "Paul", "Eddie", "John");
　$lookingFor = "Albert"; 
　if (in_array($lookingFor, $namesArray)) {
 echo "You've found it!";
} else {
 -------------------------------------------------- --------

3.count() function

If you change the value of $lookingFor and change it to "Mary", you will get the message "You' ve found it!" - because "Mary" is part of $namesArray.
If you want to count the array elements, you can use the count() function:

Copy the code

The code is as follows:

$namesArray = array("Joe", "Jane", "Bob", "Mary", "Paul", "Eddie", "John"); $count = count($ namesArray);

$count value will be 7.
-------------------------------------------------- ------------
4.array_push() function
You can add elements to any array, whether at the beginning or end of an existing array. You can also use functions to create a new array containing two or more array elements. When merged each array will be in the desired order. If your array already has internal sorting, you will need to reorder the new merged array. Let's start by adding elements to the end of an existing array, using the function array_push():

Copy the code The code is as follows:

　/* Create original array*/
　$fruitArray = array("apple", "orange", "banana", "kiwi", "pear");
　/* Join into the original array*/
array_push($fruitArray, "grape", "pineapple", "tomato");
/* List each element by its key value*/
while (list( $key,$value) = each($fruitArray)) {
　echo "$key : $value
";
　}
?>

This will Display:

Copy code The code is as follows:

apple
orange
banana
kiwi
 pear
grape
pineapple
tomato

-------------------------------- ----------------------------------
5.array_unshift() function
When The code is very similar when you need to add an element to the beginning of an array. The only difference is the function name: array_unshift() instead of array_push().

Copy code The code is as follows:

 /* Create original array*/
$ fruitArray = array("apple", "orange", "banana", "kiwi", "pear");
　/* Add to original array*/
　array_unshift($fruitArray, "grape", " pineapple", "tomato");
 /* List each element by its key value*/
while (list($key,$value) = each($fruitArray)) {
echo " $key : $value
";
　}
?>

This will display:

Copy code The code is as follows:

pineapple
tomato
apple
orange
banana
kiwi
pear

------------------------------------------------ ----------------
6.array_merge() function
Function array_merge() merges two or more arrays.

Copy code The code is as follows:

 /* Create original array*/
$ fruitArray = array("apple", "orange", "banana", "kiwi", "pear");
　/* Create a second array*/
　$vegArray = array("carrot", " green beans", "asparagus", "artichoke", "corn");
　/* Merge into an array*/
　$goodfoodArray = array_merge($fruitArray, $vegArray);
　/* Through its Key value lists each element*/
　while (list($key,$value) = each($goodfoodArray)) {
　echo "$key : $value
";
　}
?>

This will display:

Copy the codeThe code is as follows:

 apple
orange
banana
kiwi
pear
carrot
green beans
asparagus
artichoke
corn

is now available Arrays have been added and merged. Now let’s practice the element deletion function. You can use the function array_pop() to remove an element from the end of an array. If the function array_shift() is used, an element is deleted from the beginning of an array. In fact, when you delete an element from an array, the element is still available to you - when you pop or shift an element from an existing array.
-------------------------------------------------- ------------
7. array_pop() function
Use the array_pop() function to delete a value from the end of the array:

Copy code The code is as follows:

　/* Create an array*/
　$fruitArray = array("apple", "orange", "banana", "kiwi", "pear");
 /* Pop a value at the end*/
 $popped = array_pop($fruitArray);
 /* List a new array content, and the pop-up value*/
　while (list($key,$value) = each($fruitArray)) {
　echo "$key : $value
";
　}
echo "
and finally, in $popped: $popped";
?>

This will display:

Copy the codeThe code is as follows:

apple
orange
banana
kiwi 
and finally, in $popped: pear 

-------------------------- ----------------------------------
8.array_shift() function
below , delete a value from the end of the array:

Copy code The code is as follows:

　/* Create An array*/
　$fruitArray = array("apple", "orange", "banana", "kiwi", "pear");
　/* Remove a value from the head of the array*/
 $shifted = array_shift($fruitArray);
　/* List the contents of the new array and the shifted values*/
　while (list($key,$value) = each($fruitArray)) {
 echo "$key : $value
";
　}
　echo "
and finally, in $shifted: $shifted";
?>

This will display:

Copy code The code is as follows:

orange
banana
kiwi
pear and finally, in $shifted: apple

--------------------------------- --------------------------
9.sort() function
There are many functions that can help you Sort array elements. But I will demonstrate basic sorting to help you understand the process:

Copy the code The code is as follows:

　/* Create original array*/
　$fruitArray = array("apple", "orange", "banana", "kiwi", "pear");
　/* Sort*/
 Sort($fruitArray);
 /* Reset it to correctly display the array from beginning to end */
 /* List each element by its key value */
 while (list($key ,$value) = each($fruitArray)) {
　echo "$key : $value
";
　}
?>

This will display:

Copy code The code is as follows: