php数组的使用技巧,PHP数组操作汇总
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| 51自学网 2016-09-17 http://www.wanshiok.com |
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5. 数组的增添删改操作
增添数组成员
实例一：$num[] = value直接赋值追加到数组末尾：
[code]<?PHP
$num = array(1=>80,2=>120,3=>160);
echo "使用表达式添加数组成员<br />";
$num[]=240;
print_r($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
<?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<br />";
print_r($num);
echo "<br />array_pad 还可以填充数组首部<br />";
$num = array_pad($num,-8,40);
print_r($num);
?>
运行结果：
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）：
<?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
<?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！
删减数组成员
实例一：unset()命令删除数组成员或数组：
<?PHP
$num = array_fill(0,5,rand(1,10));
print_r($num);
echo "<br />";
unset($num[4]);
print_r($num);
echo "<br />";
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）
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
<?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
?>
数组，可以说是PHP的数据应用中较重要的一种方式。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。
1. 数组定义
数组的定义使用 array()方式定义，可以定义空数组：
<?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
)；
?>
2. 创建数组
compact()
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 $... ] )。
<?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:
Array (
[number] => 1,3,5,7,9
[string] => I'm PHPer
[array] => Array ( [0] => And [1] => You? )
)
array_combine()
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 )
<?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 )
range()
range()函数——创建指定范围的数组：
<?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"<br />";
$array2 = range("A","Z");
print_r($array2);
echo "<br />";
$array3 = range("z","a");
print_r($array3);
?>
array_fill()
array_fill()函数——填充数组函数：
<?PHP
$array = range(1,10);
$fillarray = range("a","d");
$arrayFilled = array_fill(0,5,$fillarray);//这里的$fillarray可以是字符串，如"test".
echo "<pre>";
print_r ($arrayFilled);
echo "</pre>";
$keys = array("string","2",9,"SDK","PK");
$array2 = array_fill_keys($keys,"testing");
echo "<pre>";
print_r ($array2);
echo "</pre>";
?>
运行结果：
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
)
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