PHP array related explanations

For web programming, the most important thing is accessing and reading and writing data. There may be many storage methods, which can be in the form of strings, arrays, files, etc.

Today I learned about arrays, which can be said to be one of the more important methods in PHP data applications. There are many array functions in PHP. The following is a summary of what I learned. I will remember it for future reference...
1. Array definition:
The definition of an array is defined using the array() method. , you can define an empty array:

Copy code The code is as follows:

$number = array(1,3 ,5,7,9);
//Define 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 comma
"week"=>array("Monday","Friday") / /The last sentence has no punctuation
);
?>

2. Create an array:
The functions included in creating an array include compact( ),
　1.compact() function - convert one or more variables (including arrays) into an array:
　　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, and of course includes array variables. 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 result:

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
=> I [3] => Am [5] => A [7] => PHP [9] => er )
　　3.range() function - Create an array within a specified range:
　　　　　　　　　　　　　　　　　　　　　　　　
#Copy code

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).

echo"
"; $array2 = range("A","Z"); print_r($array2);

$array3 = range("z","a");
print_r($array3);
?>



The default step value of the range() function it's 1!
Running results:



Copy code

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 "

"; <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
)

二、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 "

运行结果：

3.for loop traversal:

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

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