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php 数组应用详解

2024-04-30 21:10:11
 php 数组应用详解

php 数组使用详解

PHP的数组函数众多,下面是我学习的小结,借此记之,便于以后鉴之……
  一、数组定义:
  数组的定义使用 array()方式定义,可以定义空数组:
.foreach遍历:

复制代码 代码如下:
<?php
$number = array(1,3,5,7,9);
//定义空数组
$result = array();
$color =array("red","blue","green");
//自定义键值
$language = (1=>"English",3=>"Chinese",5=>"Franch");
//定义二维数组
$two = array(
"color"=>array("red","blue"), //用逗号结尾
"week"=>array("Monday","Friday") //最后一句没有标点
);
?>


二、创建数组:
  创建数组包含的函数有compact()、
    1.compact()函数――将一个或多个变量(包含数组)转换为数组:      array compact ( mixed $varname [, mixed $... ] )

复制代码 代码如下:
<?PHP
$number = "1,3,5,7,9";
$string = "I"m PHPer";
$array = array("And","You?");
$newArray = compact("number","string","array");
print_r ($newArray);
?>


compact()函数用于将两个或多个变量转换为数组,当然也包含数组变量。其参数是变量的名称而非带有$全名。
      相反的函数是extract()作用顾名思义就是将数组转换为单个的字符串,键值作为其字符串名称,数组值作为字符串的值。
      运行结果:

复制代码 代码如下:
Array ( [number] => 1,3,5,7,9 [string] => I"m PHPer [array] => Array ( [0] => And [1] => You? ) )


2.array_combine()――将两个数组重组成一个数组,一个作键值一个做的值:      array array_combine ( array $keys , array $values )

复制代码 代码如下:
<?PHP
$number = array("1","3","5","7","9");
$array = array("I","Am","A","PHP","er");
$newArray = array_combine($number,$array);
print_r ($newArray);
?>


array_combine函数不多说了,谁看了都明白
      运行结果:
Array ( [1] => I [3] => Am [5] => A [7] => PHP [9] => er )
    3.range()函数――创建指定范围的数组:       不多说了,直接上实例――

复制代码 代码如下:
<?PHP
$array1 = range(0,100,10);//0为起始值,100为结束值,10为步进值(默认步进值为1).
print_r($array1);
echo"
";
$array2 = range("A","Z");
print_r($array2);
echo "
";
$array3 = range("z","a");
print_r($array3);
?>


range()函数的默认步进值是1!
      运行结果:

复制代码 代码如下:
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:
<?PHP
$array = range(1,10);
$fillarray = range("a","d");
$arrayFilled = array_fill(0,5,$fillarray);//这里的$fillarray可以是字符串,如"test".
echo "
"; 
print_r ($arrayFilled);
echo "
";
$keys = array("string","2",9,"SDK","PK");
$array2 = array_fill_keys($keys,"testing");
echo "
"; 
print_r ($array2);
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:
<?PHP
$speed = array(50,120,180,240,380);
foreach($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:
<?PHP
$staff = array(
array("姓名","性别","年龄"),
array("小张","男",24),
array("小王","女",25),
array("小李","男",23)
);
echo "";
while(list($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 24
小王 25
小李 23

3.for循环遍历:

复制代码 代码如下:
<?PHP
$speed = range(0,220,20);
for($i =0;$i echo $speed[$i]." ";
}
?>


运行结果:

复制代码 代码如下:
0 20 40 60 80 100 120 140 160 180 200 220


四、数组的指针操作:
    涉及函数包括reset、prev、end、next、current、each
实例一:

复制代码 代码如下:
<?PHP
$speed = range(0,220,20);
echo current($speed);//输出当前位置的值(在数组的开头位置)
$i = rand(1,11);
while($i--){
next($speed);//指针从当前位置向后移动一位
}
echo current($speed);//输出当前位置的值
echo "
";
echo prev($speed);//输出前一位置数组值
echo "
";
echo reset($speed);//重置数组的指针,将指针指向起始位置
echo "
";
echo end($speed);//输出最后位置的数组值
echo "
";
?>


运行结果:

复制代码 代码如下:
0220
200
0
220


实例二:each函数指针操作

复制代码 代码如下:
<?PHP
$speed = range(0,200,40);
echo "each实现指针下移
";
echo "0挡的速度是".current(each($speed))."
";
echo "1挡的速度是".current(each($speed))."
";
echo "2挡的速度是".current(each($speed))."
";
echo "3挡的速度是".current(each($speed))."
";
echo "4挡的速度是".current(each($speed))."
";
echo "5挡的速度是".current(each($speed))."
";
echo "使用each函数实现数组指针的移动,进行数组遍历
";
reset($speed);//这里是将数组指针指向数组首
while(list($key,$value)=each($speed)){
echo $key."=>".$value."
";
}
?>


运行结果:

复制代码 代码如下:
each实现指针下移
0挡的速度是0
1挡的速度是40
2挡的速度是80
3挡的速度是120
4挡的速度是160
5挡的速度是200
使用each函数实现数组指针的移动,进行数组遍历
0=>0
1=>40
2=>80
3=>120
4=>160
5=>200


五、数组的增添删改操作:
    1.增添数组成员:实例一:$num[] = value直接赋值追加到数组末尾:

复制代码 代码如下:
<?PHP
$num = array(1=>80,2=>120,3=>160);
echo "使用表达式添加数组成员
";
$num[]=240;
print_r($num);
?>


运行结果:
使用表达式添加数组成员Array ( [0] => 80 [1] => 120 [2] => 160 [3] => 240 )
实例二:array_pad函数,数组数组首尾选择性追加

复制代码 代码如下:
<?PHP
$num = array(1=>80,2=>120,3=>160);
$num = array_pad($num,4,200);
echo "使用array_pad函数向数组尾部添加成员
";
print_r($num);
echo "
array_pad 还可以填充数组首部
";
$num = array_pad($num,-8,40);
print_r($num);
?>


运行结果:

复制代码 代码如下:
使 用array_pad函数向数组尾部添加成员Array ( [0] => 80 [1] => 120 [2] => 160 [3] => 200 ) array_pad 还可以填充数组首部Array ( [0] => 40 [1] => 40 [2] => 40 [3] => 40 [4] => 80 [5] => 120 [6] => 160 [7] => 200 )


实例三:入栈操作追加(array_push):

复制代码 代码如下:
<?PHP
$num = array(1=>80,2=>120,3=>160);
array_push($num,200,240,280);//可以自己追加,直接加在数组结尾
print_r($num);
?>


运行结果:
Array ( [1] => 80 [2] => 120 [3] => 160 [4] => 200 [5] => 240 [6] => 280 )
实例四:array_unshift()在开头添加数组成员

复制代码 代码如下:
<?PHP
$num = array(1=>80,2=>120,3=>160);
array_unshift($num,0,40);//可以自己追加,直接加在数组结尾
print_r($num);
?>


运行结果:
Array ( [0] => 0 [1] => 40 [2] => 80 [3] => 120 [4] => 160 )
注意:array_unshift()函数使用后数组的键值将会从0开始!
     2.删减数组成员:
实例一:unset()命令删除数组成员或数组:

复制代码 代码如下:
<?PHP
$num = array_fill(0,5,rand(1,10));
print_r($num);
echo "
";
unset($num[4]);
print_r($num);
echo "
";
unset($num);
if(is_array){
echo "unset命令不能删除整个数组";
}else{
echo "unset命令可以删除数组";
}
?>


运行结果:(运行出错及说明数组也被删除,不再存在)

复制代码 代码如下:
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:\wamp\www\testing\editorplus\test.php on line 21
unset命令不能删除整个数组


实例二:array_splice()函数删除数组成员

复制代码 代码如下:
<?php
$a=array("red", "green", "blue", "yellow");
count ($a); //得到4
array_splice($a,1,1); //删除第二个元素
count ($a); //得到3
echo $a[2]; //得到yellow
echo $a[1]; //得到blue
?>


实例三:array_unique删除数组中的重复值:

复制代码 代码如下:
<?php
$a=array("red", "green", "blue", "yellow","blue","green");
$result = array_unique($a);
print_r($result);
?>


运行结果:
Array ( [0] => red [1] => green [2] => blue [3] => yellow )
实例四:array_merge、array_merge_recursive合并数组

复制代码 代码如下:
<?php
$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 "
"; 
print_r($result);
echo "
";
$result = array_merge_recursive($array1,$array2,$array3,$array4,$array5);
echo "
"; 
print_r ($result);
echo "
";
?>


运行结果:

复制代码 代码如下:
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:
<?php
$array = range(0,9);
if(in_array(9,$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:
<?php
$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:
<?PHP
$staff = array(
array("姓名","性别","年龄"),
array("小张","男",24),
array("小王","女",25),
array("小李","男",23)
);
echo "";
while(list($keys,$value) = each($staff)){
list($name,$sex,$age) = $value;
echo "";
}
echo "
$name $sex $age
";
?>


运行结果:


实例四:array_flip()交换数组的键值和值:

复制代码 代码如下:
<?PHP
$array = array("red","blue","yellow","Black");
print_r($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:
<?PHP
$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 )


实例六:array_search()搜索数值:

复制代码 代码如下:
<?PHP
$array = array("red","blue","yellow","Black");
$result = array_search("red",$array);
if(($result === NULL)){
echo "不存在数值red";
}else{
echo "存在数值 $result";
}
?>


结果:存在数值 0
函数array_search()返回的值可能为false或0或NULL,所以在判断时注意要用"==="
  七、数组的排序:
实例一:sort()、rsort()/asort()、arsort()对数组排序:

复制代码 代码如下:
<?PHP
$array = array("b","c","d","a");
sort($array);//从低到高排序
print_r($array);
echo "
";
rsort($array);//逆向排序
print_r($array);
?>


结果:
Array ( [0] => a [1] => b [2] => c [3] => d )
Array ( [0] => d [1] => c [2] => b [3] => a )
sort()、rsort()函数对数组进行从低到高的排序,返回结果为bool值;
asort()、arsort()函数是保留键值的排序,排序后键值不重新索引。
实例二:将数组顺序打乱――shuffle()函数:

复制代码 代码如下:
<?PHP
$array = array("a","b","c","d");
shuffle($array);//从低到高排序
print_r($array);
?>


结果为动态结果:
Array ( [0] => c [1] => a [2] => d [3] => b )
shuffle的结果有点随机的意味,每次刷新都不一样。

实例三:array_reverse()数组反向:

复制代码 代码如下:
<?PHP
$array = array("d","b","a","c");
$array = array_reverse($array);//从低到高排序
print_r($array);
?>


运行结果:
Array ( [0] => c [1] => a [2] => b [3] => d )
实例四:自然排序算法――natsort()和natcasesort();

复制代码 代码如下:
<?PHP
$array = array("sort2","Sort5","sort1","sort4");
natsort($array);//从低到高排序
print_r($array);
echo "
";
natcasesort($array);
print_r($array);
?>


结果:
Array ( [1] => Sort5 [2] => sort1 [0] => sort2 [3] => sort4 )
Array ( [2] => sort1 [0] => sort2 [3] => sort4 [1] => Sort5 )
natsort()、natcasesort()对数组进行自然排序,就是使用数字的正常排序算法。natcasesort会忽略大小写。
实例五:对数组进行键值排序ksort():

复制代码 代码如下:
<?PHP
$array = array(1=>"sort2",4=>"Sort5",2=>"sort1",3=>"sort4");
ksort($array);//从低到高排序
print_r($array);
?>


结果:
Array ( [1] => sort2 [2] => sort1 [3] => sort4 [4] => Sort5 )
注意:ksort()函数重新建立了索引。
八、数组的其他用法:
  cout($array) --------统计数组的单元个数
  array_diff($array1,$array2)----------统计数组之间的不同点,返回第一个数组中有而第二个数组中没有的。
  array_diff_assoc($array1,$array2)---------同array_diff(),只是它对键值也比较
  array_diff_key($array1,$array2)------------比较键值
  array_product($array)-----------返回数组的所有数的乘积
  array_sum($array)--------------所有数值的和
  array_rand($array,$n)----------在$array数组中取出$n个数值,返回数组
  array_intersect($array1,$array2)----------------取得两个数组的交集
  array_intersect_assoc($array1,$array2)---------------在array_intersect 的基础上进行键值比较
  array_intersect_key($array1,$array2)-----------------比较两个数组键值的交集
  总结:
  数组的使用在PHP中至关重要,由于PHP没有指针,所以数组承担了很大的数据操作任务。学好数组,才能把PHP应用的得心应手,这里所列均是常用的PHP数组相关的函数及用法,欢迎一起学习!