Detailed explanation of the use of php arrays Recommended

There are many array functions in PHP. The following is a summary of what I learned. I will write it down for future reference...
1. Array definition:
The definition of an array is defined using the array() method. , you can define an empty array:
.foreach traversal:

Copy code The code is as follows:

 
$number = array(1,3,5,7,9); 
//Define an empty array
$result = array(); 
$color =array("red","blue ","green"); 
//Custom key value
$language = (1=>"English",3=>"Chinese",5=>"Franch"); 
//Define a two-dimensional array
$two = array( 
"color"=>array("red","blue"), //End with a comma
"week"=>array ("Monday","Friday") //The last sentence has no punctuation 
); 
?> 

2. Create an array:
Create The functions included in the array include compact(),
1. compact() function - convert one or more variables (including arrays) into arrays: array compact ( mixed $varname [, mixed $... ] ) 🎜>

Copy code The code is as follows:

$number = "1,3,5,7, 9"; 
$string = "I'm PHPer"; 
$array = array("And","You?"); 
$newArray = compact("number","string", "array"); 
print_r ($newArray); 
?> 

 

compact() function is used to convert two or more variables into arrays, including arrays of course variable. The parameter is the name of the variable rather than the full name with $.
　　　The opposite function is extract(). As the name suggests, it converts the array into a single string, with the key value as its string name and the array value as the string value.
Running results:

Copy code The code is as follows:

Array ( [number] => 1,3, 5,7,9 [string] => I'm PHPer [array] => Array ( [0] => And [1] => You? ) ) 

 

2 .array_combine()——Reorganize two arrays into one array, one as the key value and the other as the value: array array_combine ( array $keys , array $values )

Copy code The code is as follows:

$number = array("1","3","5","7","9"); 
$array = array("I","Am","A","PHP","er"); 
$newArray = array_combine($number,$array); 
print_r ($ newArray); 
?> 

 

I won’t go into detail about the array_combine function, everyone will understand it after reading it
Running results:
Array ( [1] => I [3 ] => Am [5] => A [7] => PHP [9] => er )

　3. range() function - Create an array within a specified range: Not much to say Now, go directly to the example -

Copy the code The code is as follows:

$ array1 = range(0,100,10);//0 is the starting value, 100 is the end value, and 10 is the step value (the default step value is 1). 
print_r($array1); 
echo" 
"; 
$array2 = range("A","Z"); 
print_r($array2); 
echo "
"; 
 $array3 = range("z","a"); 
print_r($array3); 
?> 

 

The default step value of the range() function is 1!
Running results:

Copy code The code is as follows:

Array ( [0] => 0 [1] => 10 [2] => 20 [3] => 30 [4] => 40 [5] => 50 [6] => 60 [7] => 70 [8] = > 80 [9] => 90 [10] => 100 ) Array ( [0] => A [1] => B [2] => C [3] => D [4 ] => E [5] => F [6] => G [7] => H [8] => I [9] => J [10] => K [11] => L [12] => M [13] => N [14] => O [15] => P [16] => Q [17] => R [18] = > S [19] => T [20] => U [21] => V [22] => W [23] => X [24] => Y [25] => ; Z ) Array ( [0] => z [1] => y [2] => x [3] => w [4] => v [5] => u [6] => t [7] => s [8] => r [9] => q [10] => p [11] => o [12] => n [13] = > m [14] => l [15] => k [16] => j [17] => i [18] => h [19] => g [20] => ; f [21] => e [22] => d [23] => c [24] => b [25] => a )

4.array_fill()函数——填充数组函数：

复制代码代码如下:

$array = range(1,10);
$fillarray = range("a","d");
$arrayFilled = array_fill(0,5,$fillarray);//这里的$fillarray可以是字符串，如"test".
echo "

"; <br>print_r ($arrayFilled); <br>echo "

";
$keys = array("string","2",9,"SDK","PK");
$array2 = array_fill_keys($keys,"testing");
echo "

"; <br>print_r ($array2); <br>echo "

";
?>

运行结果：

复制代码代码如下:

 
Array 
( 
[0] => Array 
( 
[0] => a 
[1] => b 
[2] => c 
[3] => d 
) 
[1] => Array 
( 
[0] => a 
[1] => b 
[2] => c 
[3] => d 
) 
[2] => Array 
( 
[0] => a 
[1] => b 
[2] => c 
[3] => d 
) 
[3] => Array 
( 
[0] => a 
[1] => b 
[2] => c 
[3] => d 
) 
[4] => Array 
( 
[0] => a 
[1] => b 
[2] => c 
[3] => d 
) 
) 
Array 
( 
[string] => testing 
[2] => testing 
[9] => testing 
[SDK] => testing 
[PK] => testing 
) 

三、数组的遍历：
　　　　1.foreach遍历：　　　　　　　foreach (array_expression as $value){}
　　　　　　　foreach (array_expression as $key => $value){}
　　　　　　闲话少说，上实例：

复制代码代码如下:

 
$speed = array(50,120,180,240,380); 
foreach($speed as $keys=>$values){ 
echo $keys."=>".$values."
"; 
} 
?> 

运行结果：

复制代码代码如下:

 
0=>50 
1=>120 
2=>180 
3=>240 
4=>380 

2.while循环遍历：
while循环遍历一般结合list函数，以下是实例

复制代码代码如下:

 
$staff = array( 
array("姓名","性别","年龄"), 
array("小张","男",24), 
array("小王","女",25), 
array("小李","男",23) 
); 
echo ""; 
while(list($keys,$value) = each($staff)){ 
list($name,$sex,$age) = $value; 
echo ""; 
} 
echo "$name$sex$age
"; 
?> 

运行结果：

姓名	性别	年龄
小张	男	24
小王	女	25
小李	男	23

3. The for loop traverses:

Copy code The code is as follows:

 
$speed = range( 0,220,20); 
for($i =0;$iecho $speed[$i]." "; 
} 
? > 

Run result:

Copy code The code is as follows:

0 20 40 60 80 100 120 140 160 180 200 220

4. Array pointer operations:
Functions involved include reset, prev, end, next, current, each
Example 1:

Copy code The code is as follows:

 
$speed = range(0,220,20); 
echo current($speed);//Output the value of the current position (at the beginning of the array) 
$i = rand(1,11); 
while($i--){ 
next($ speed);//Move the pointer one position backward from the current position
} 
echo current($speed);//Output the value of the current position
echo "
"; 
echo prev($speed);//Output the previous position array value
echo "
"; 
echo reset($speed);//Reset the pointer of the array and point the pointer to Starting position
echo "
"; 
echo end($speed);//Output the array value of the last position
echo "
"; 
 ?> 

Run result:

Copy code The code is as follows:

0220
200
0
220

Example 2: each function pointer operation

Copy code The code is as follows:

 
$speed = range(0,200,40); 
echo "each moves the pointer down
"; 
echo "0 block The speed of 1st gear is ".current(each($speed))."
"; 
echo "The speed of 1st gear is ".current(each($speed))."
echo "The speed of 2nd gear is".current(each($speed))."
"; 
echo "The speed of 3rd gear is".current(each($ speed))."
"; 
echo "The speed of 4th gear is".current(each($speed))."
"; 
echo "5th gear The speed is ".current(each($speed))."
"; 
echo "Use each function to move the array pointer and perform array traversal
"; 
reset($speed);//This is to point the array pointer to the beginning of the array
while(list($key,$value)=each($speed)){ 
echo $key."=>" .$value."
"; 
} 
?> 

Running result:

Copy code The code is as follows:

 
each moves the pointer downwards 
The speed of 0 gear is 0 
The speed of 1st gear is 40 
The speed of 2nd gear is 80 
The speed of 3rd gear is 120 
The speed of 4th gear is 160 
The speed of 5th gear is 200 
Use each function to move the array pointer and perform array traversal 
0=>0 
1=>40 
2=>80 
3=>120 
4=>160 
5=>200 

5. Add and delete operations of the array:
　1. Add array members: Example 1: $num[] = value is directly assigned and appended to the end of the array:

Copy code The code is as follows:

 
$num = array(1=>80,2=>120,3=>160); 
echo "use Expression adds array members
"; 
$num[]=240; 
print_r($num); 
?> 

Running result:
Use expression to add array member Array ( [0] => 80 [1] => 120 [2] => 160 [3] => 240 )
Example 2: array_pad function, array Selective append to the beginning and end of the array

Copy code The code is as follows:

 
$num = array(1 =>80,2=>120,3=>160); 
$num = array_pad($num,4,200); 
echo "Use the array_pad function to add members to the end of the array
print_r($num); 
echo "
array_pad can also fill the head of the array
"; 
$num = array_pad($num,-8 ,40); 
print_r($num); 
?> 

Running result:

Copy codeThe code is as follows:

 
Use the array_pad function to add member Array to the end of the array ( [0] => 80 [1] => 120 [2] => 160 [3] => 200 ) array_pad can also fill the array Header Array ([0] => 40 [1] => 40 [2] => 40 [3] => 40 [4] => 80 [5] => 120 [6] => ; 160 [7] => 200 ) 

Example 3: Stack operation append (array_push):

Copy code The code is as follows:

 
$num = array(1=>80,2=>120,3=>160); 
array_push($num ,200,240,280);//You can append by yourself, directly at the end of the array 
print_r($num); 
?> 

Operating result:
Array ( [1] => 80 [2] => 120 [3] => 160 [4] => 200 [5] => 240 [6] => 280 )
Example 4: array_unshift() in Add array members at the beginning

Copy code The code is as follows:

 
$num = array(1= >80,2=>120,3=>160); 
array_unshift($num,0,40);//You can append by yourself, directly at the end of the array
print_r($num); 
?> 

Run result:
Array ( [0] => 0 [1] => 40 [2] => 80 [3] => 120 [4] => 160 )
Note: After using the array_unshift() function, the key value of the array will start from 0!
　　2. Delete array members:
Example 1: The unset() command deletes array members or arrays:

Copy code The code is as follows:

 
$num = array_fill(0,5,rand(1,10)); 
print_r($num); 
echo "
"; 
unset($num[4]); 
print_r($num); 
echo "
"; 
unset($num); 
 if(is_array){ 
echo "The unset command cannot delete the entire array"; 
}else{ 
echo "The unset command can delete the array"; 
} 
?> 

Running result: (Running error and description array are also deleted and no longer exist)

Copy code The code is as follows:

 
Array ( [0] => 9 [1] => 9 [2] => 9 [3] => 9 [4] => 9 ) 
Array ( [0] => 9 [1] => 9 [2] => 9 [3] => 9 ) 
Notice: Use of undefined constant is_array - assumed 'is_array' in H:wampwwwtestingeditorplustest.php on line 21 
The unset command cannot delete the entire array

Example 2: array_splice() function deletes array members

Copy code The code is as follows :

 
$a=array("red", "green", "blue", "yellow"); 
count ($a); // Get 4 
array_splice($a,1,1); //Delete the second element
count ($a); //Get 3 
echo $a[2]; //Get yellow 
echo $a[1]; //get blue 
?> 

Example 3: array_unique deletes duplicate values in the array:

Copy code The code is as follows:

 
$a=array("red", "green", "blue", "yellow"," blue","green"); 
$result = array_unique($a); 
print_r($result); 
?> 

Run result:
Array ( [0] => red [1] => green [2] => blue [3] => yellow )
Example 4: array_merge, array_merge_recursive merge arrays

Copy code The code is as follows:

$array1 = array("r"=>"red",1,2, 3,4);
$array2 = array("b"=>"blue",4=>5,6,7,8,9);
$array3 = array("r"= >"read",4=>10,2=>11);
$array4 = array(
array(4=>10),
array(7=>13)
);
$array5 = array(
array(4=>11),
array(6=>12)
);
$result = array_merge($ array1,$array2,$array3,$array4,$array5);
echo "

"; <br>print_r($result); <br>echo "

";
$result = array_merge_recursive($array1,$array2,$array3,$array4,$array5);
echo "

"; 
print_r ($result); 
echo "?>

Run result:

Copy code The code is as follows:

 
Array 
( 
[r] => read 
[0] => 1 
[1] => 2 
[2] => 3 
[3] => 4 
[b] => blue 
[4] => 5 
[5] => 6 
[6] => 7 
[7] => 8 
[8] => 9 
[9] => 10 
[10] => 11 
[11] => Array 
( 
[4] => 10 
) 
[12] => Array 
( 
[7] => 13 
) 
[13] => Array 
( 
[4] => 11 
) 
[14] => Array 
( 
[6] => 12 
) 
) 
Array 
( 
[r] => Array 
( 
[0] => red 
[1] => read 
) 
[0] => 1 
[1] => 2 
[2] => 3 
[3] => 4 
[b] => blue 
[4] => 5 
[5] => 6 
[6] => 7 
[7] => 8 
[8] => 9 
[9] => 10 
[10] => 11 
[11] => Array 
( 
[4] => 10 
) 
[12] => Array 
( 
[7] => 13 
) 
[13] => Array 
( 
[4] => 11 
) 
[14] => Array 
( 
[6] => 12 
) 
) 

注：1.array_merge的键名是数字的将重新建立索引；遇到相同的字符串键名时，后面的将覆盖前面的。
　　2.array_merge_recursive函数的作用是将相同字符串的键名单元整合成一个数组。
　　六、数组的键值和值操作：
实例一：in_array()检测数组中是否有某个值存在

复制代码代码如下:

 
$array = range(0,9); 
if(in_array(9,$array)){ 
echo "数组中存在"; 
} 
?> 

运行结果：
数组中存在
实例二：key()取得数组当前的键名：

复制代码代码如下:

 
$array = range(0,9); 
$num = rand(0,8); 
while($num--) 
next($array); 
$key = key($array); 
echo $key; 
?> 

此实例结果为动态结果，范围（0-8），不做结果演示。
实例三：list()函数把数组中的值赋给指定变量：

复制代码代码如下:

 
$staff = array( 
array("姓名","性别","年龄"), 
array("小张","男",24), 
array("小王","女",25), 
array("小李","男",23) 
); 
echo ""; 
while(list($keys,$value) = each($staff)){ 
list($name,$sex,$age) = $value; 
echo ""; 
} 
echo "$name$sex$age
"; 
?> 

运行结果：

Detailed explanation of the use of php arrays Recommended_PHP tutorial

实例四：array_flip()交换数组的键值和值:

复制代码代码如下:

 
$array = array("red","blue","yellow","Black"); 
print_r($array); 
echo "
"; 
$array = array_flip($array); 
print_r($array); 
?> 

运行结果：

复制代码代码如下:

 
Array ( [0] => red [1] => blue [2] => yellow [3] => Black ) 
Array ( [red] => 0 [blue] => 1 [yellow] => 2 [Black] => 3 ) 

实例五：array_keys()、array_values()返回数组中所有的键值和值：

复制代码代码如下:

 
$array = array("red","blue","yellow","Black"); 
$result = array_keys($array); 
print_r($result); 
echo "
"; 
$result = array_values($array); 
print_r($result); 
?> 

运行结果：

复制代码代码如下:

 
Array ( [0] => 0 [1] => 1 [2] => 2 [3] => 3 ) 
Array ( [0] => red [1] => blue [2] => yellow [3] => Black ) 

Example 6: array_search() search value:

Copy code The code is as follows:

 
$array = array("red","blue","yellow","Black"); 
$result = array_search("red",$array); 
if(($result === NULL)){ 
echo "The value red does not exist"; 
}else{ 
echo "The value $result exists"; 
} 
?> 

Result: There is a value 0
The value returned by the function array_search() may be false or 0 or NULL, so be careful to use "==="
7. Sorting of arrays:
Example 1 : sort(), rsort()/asort(), arsort() to sort the array:

Copy code The code is as follows:

 
$array = array("b","c","d","a"); 
sort($array);//Sort from low to high
 print_r($array); 
echo "
"; 
rsort($array);//Reverse sort
print_r($array); 
?> 
 

Result:
Array ( [0] => a [1] => b [2] => c [3] => d )
Array ( [0] => d [1] => c [2] => b [3] => a )
The sort() and rsort() functions sort the array from low to high, and the return result is bool value;
asort() and arsort() functions preserve the sorting of key values, and the key values are not re-indexed after sorting.
Example 2: Disturbing the order of the array - shuffle() function:

Copy code The code is as follows:

 
 $array = array("a","b","c","d"); 
shuffle($array);//Sort from low to high
print_r( $array); 
?> 

The result is a dynamic result:
Array ( [0] => c [1] => a [2] => d [3] => b)
The result of shuffle is a bit random and different every time it is refreshed.

Example 3: array_reverse() array reverse:

Copy code The code is as follows:

 
< ?PHP 
$array = array("d","b","a","c"); 
$array = array_reverse($array);//Sort from low to high
print_r ($array); 
?> 

Run result:
Array ( [0] => c [1] => a [2] => b [ 3] => d )
Example 4: Natural sorting algorithm - natsort() and natcasesort();

Copy code The code is as follows:

 
$array = array("sort2","Sort5","sort1","sort4"); 
natsort($array);//from low Sort to high 
print_r($array); 
echo "
"; 
natcasesort($array); 
print_r($array); 
?> 

Result:
Array ( [1] => Sort5 [2] => sort1 [0] => sort2 [3] => sort4 )
Array ( [ 2] => sort1 [0] => sort2 [3] => sort4 [1] => Sort5 )
natsort() and natcasesort() perform natural sorting on the array, which is the normal sorting using numbers algorithm. natcasesort ignores case.
Example 5: Sort arrays by key value ksort():

Copy code The code is as follows:

 
< ?PHP 
$array = array(1=>"sort2",4=>"Sort5",2=>"sort1",3=>"sort4"); 
ksort($array ); // Sort from low to high 
print_r($array); 
?> 

Result:
Array ( [1] => sort2 [2] => sort1 [3] => sort4 [4] => Sort5 )
Note: ksort() function is re-established indexed.
8. Other uses of arrays:
cout($array) -------- Count the number of units in an array
array_diff($array1,$array2)------ --- Count the differences between arrays and return what is in the first array but not in the second array.
　array_diff_assoc($array1,$array2)----------Same as array_diff(), except that it also compares key values
　array_diff_key($array1,$array2)---------- -----Compare key values
　array_product($array)-----------Return the product of all numbers in the array
　array_sum($array)-------- ------The sum of all values
　array_rand($array,$n)----------Take out $n values in the $array array and return the array
　array_intersect($ array1,$array2)----------------Get the intersection of two arrays
　array_intersect_assoc($array1,$array2)------------ ---Compare key values based on array_intersect
　array_intersect_key($array1,$array2)-----------------Compare the intersection of two array key values
Summary:
The use of arrays is crucial in PHP. Since PHP does not have pointers, arrays bear a large number of data manipulation tasks. Only by learning arrays well can you apply PHP with ease. Listed here are the commonly used functions and usage related to PHP arrays. Welcome to learn together!