PHP array learning

For Web programming, the most important thing is to access and read/write data. There may be many storage methods, which can be strings, arrays, files, etc. today I learned arrays. it can be said that it is an important method in PHP Data applications. PHP has a large number of array functions. The following is a summary of my learning, so that you can easily identify them later ......
I. array definition:
The array definition uses the array () method to define an empty array:
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 contains no punctuation.
);
?>

2. create an array:
Create the functions included in the array: compact (),
1. compact () function -- convert one or more variables (including arrays) to an array:
Array compact (mixed $ varname [, mixed $...])
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 );
?>

The compact () function is used to convert two or more variables to an array. of course, it also contains array variables. The parameter is the variable name, not the $ full name.
The opposite function is extract (). as the name suggests, it is to convert an array into a single string. The key value is used as the string name, and the array value is used as the string value.
Running result:
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 () -- combines two arrays into an array, one as the key value and the other as the value:
Array array_combine (array $ keys, array $ values)
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 );
?>

No more about the array_combine function.
Running result:

Array ([1] => I [3] => Am [5] => A [7] => PHP [9] => er)
3. range () function -- create an array of the specified range:
Let's just move on to the instance directly --
The code is as follows:
$ Array1 = range (0,100, 10); // 0 indicates the start value, 100 indicates the end value, and 10 indicates the step value (the default step value is 1 ).
Print_r ($ array1 );
Echo"
";
$ Array2 = range ("A", "Z ");
Print_r ($ array2 );
Echo"
";
$ Array3 = range ("z", "");
Print_r ($ array3 );
?>

The default step value of the range () function is 1!
Running result:
The code is as follows:
Array ([0] => 0 [1] => 10 [2] => 20 [3] => 30 [4] => 40 [5] => 50 [6] = & gt; 60 [7] = & gt; 70 [8] = & gt; 80 [9] = & gt; 90 [10] = & gt; 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] =>)

4. array_fill () function -- fill the array function:
The code is as follows:
$ Array = range (1, 10 );
$ Fillarray = range ("a", "d ");
$ ArrayFilled = array_fill (, $ fillarray); // $ fillarray can be a string, such as "test ".
Echo"

"; 
print_r ($arrayFilled); 
echo "

";
$ Keys = array ("string", "2", 9, "SDK", "PK ");
$ Array2 = array_fill_keys ($ keys, "testing ");
Echo"

"; 
print_r ($array2); 
echo "

";
?>

Running result:
The code is as follows:
Array
(
[0] => Array
(
[0] =>
[1] => B
[2] => c
[3] => d
)
[1] => Array
(
[0] =>
[1] => B
[2] => c
[3] => d
)
[2] => Array
(
[0] =>
[1] => B
[2] => c
[3] => d
)
[3] => Array
(
[0] =>
[1] => B
[2] => c
[3] => d
)
[4] => Array
(
[0] =>
[1] => B
[2] => c
[3] => d
)
)
Array
(
[String] => testing
[2] => testing
[9] => testing
[SDK] => testing
[PK] => testing
)

II. array traversal:
1. foreach traversal:
Foreach (array_expression as $ value ){}
Foreach (array_expression as $ key => $ value ){}
For example:
The code is as follows:
$ Speed = array (50,120,180,240,380 );
Foreach ($ speed as $ keys => $ values ){
Echo $ keys. "=>". $ values ."
";
}
?>

Running result:
The code is as follows:
0 => 50
1 => 120
2 => 180
3 => 240
4 => 380

2. while loop traversal:
While loop traversal is generally combined with the list function, the following is an instance
The code is as follows:
$ Staff = array (
Array ("name", "gender", "age "),
Array ("Xiao Zhang", "male", 24 ),
Array ("Wang", "female", 25 ),
Array ("Xiao Li", "male", 23)
);
Echo"




";While (list ($ keys, $ value) = each ($ staff )){List ($ name, $ sex, $ age) = $ value;Echo" ";}Echo"

$ Name

$ Sex

$ Age

";
?>

Running result:

Name	Gender	Age
Xiao Zhang	Male	24
John	Female	25
Xiao Li	Male	23

3. for loop traversal:
The code is as follows:
$ Speed = range (0,220, 20 );
For ($ I = 0; $ I Echo $ speed [$ I]. "";
}
?>

Running result:
The code is as follows:
0 20 40 60 80 100 120 140 160 180 200