php常用函数-数组

学习php的过程中，整理的一些常用的函数，这是数组函数。

<?php
//array():生成一个数组
$a = array("dog","cat","horse");
print_r($a); //Array ( [0] => dog [1] => cat [2] => horse )

//array_combine():生成一个数组，用一个数组的值作为键名，另一个数组的值作为值
$a1 = array("a","b","c","d");
$a2 = array("Cat","Dog","Horse","Cow");
print_r(array_combine($a1,$a2)); //Array ( [a] => Cat [b] => Dog [c] => Horse [d] => Cow )

//range():创建并返回一个包含指定范围的元素的数组。
$number = range(0,50,10); //(0:序列的第一个值；50：序列结束值；10：每次的步长)
print_r ($number); //Array ( [0] => 0 [1] => 10 [2] => 20 [3] => 30 [4] => 40 [5] => 50 )

//compact():创建一个由参数所带变量组成的数组
$firstname = "Peter";
$lastname = "Griffin";
$age = "38";
$result = compact("firstname", "lastname", "age");
print_r($result); //Array ( [firstname] => Peter [lastname] => Griffin [age] => 38 )

//array_fill():用给定的值生成数组
$a = array_fill(2,3,"Dog"); //(2：填冲的第一个键值；3：填冲的数值；dog：填冲的内容)
print_r($a); //Array ( [2] => Dog [3] => Dog [4] => Dog )

//array_chunk():把一个数组分割为新的数组块
$a = array("a"=>"cat","b"=>"dog","c"=>"horse","d"=>"Cow");
print_r(array_chunk($a,2)); //Array([0] => Array([a]=>cat [b]=>dog) [1] => Array([c]=>horse [d]=>cow))

//array_merge():把两个数组合并为一个数组
/***********************与array_combine区别***********************
array_merge():直接合并数组；array_combine():根据参数顺序第一组为键，第二组为值;*/
echo "<hr/>";
$a1 = array("a"=>"Horse","b"=>"Dog");
$a2 = array("c"=>"Cow","b"=>"cat");
print_r(array_merge($a1,$a2)); //Array ( [a] => Horse [b] => Dog [c] => Cow [d] => cat )

//array_diff():返回两个数组的差集（键名保持不变）
$a1 = array(8=>"Cat",1=>"Dog",2=>"Horse",3=>"lion");
$a2 = array(4=>"Horse",5=>"Dog",6=>"bird",7=>"pig");
print_r(array_diff($a1,$a2)); //Array ( [8] => Cat [3] => lion )
print_r(array_diff($a2,$a1)); //Array ( [6] => bird [7] => pig )

//array_intersect():返回两个或多个数组的交集数组
$a1 = array(0=>"Cat",1=>"Dog",2=>"Horse");
$a2 = array(3=>"Horse",4=>"Dog",5=>"Fish");
print_r(array_intersect($a1,$a2)); // Array ( [1] => Dog [2] => Horse )
print_r(array_intersect($a2,$a1)); // Array ( [3] => Horse [4] => Dog )

//array_serach在数组中搜索给定的值，如果成功则返回相应的键名（失败返回false）
$a = array("a"=>"Dog","b"=>"Cat","c"=>"Horse");
echo array_search("Dog",$a); //a

//array_slice():在数组中根据条件取出一段值，并返回(键名保持不变)
echo "<br/>";
$a = array("a"=>"Dog","b"=>"Cat","c"=>"Horse","d"=>"Bird");
print_r(array_slice($a,1,2)); //1：从键值(相当于索引键为1的位置开始取)；2，取两个
//Array ( [b] => Cat [c] => Horse )

//array_splice():把数组中的一部分去掉，并用其它的值取代
$a1 = array(4=>"Dog",'b'=>"Cat",'c'=>"Horse",6=>"Bird");
$a2 = array(3=>"Tiger",5=>"Lion");
array_splice($a1,1,2,$a2);
/* $a1:被替换的数组（最后被输出的数组）;1:按索引键的1位置开始替换；2：替换两个；$a2:替换数组,加到$a1中去 */
print_r($a1); //Array ( [0] => Dog [1] => Tiger [2] => Lion [3] => Bird )
//array_splice($a1,0,2,$a2);
//print_r($a1); // Array ( [0] => Tiger [1] => Lion [2] => Horse [3] => Bird )

//array_sum():计算数组中所有值的和
$a = array(0=>"5",1=>"15",2=>"25");
echo array_sum($a); //45

//in_array():检查数组中是否存在某个值
$animals = array("dog", "cat", "cow", "horse");
if (in_array("cow",$animals)){
echo "Match found";
}else{
echo "Match not found";
}

//array_key_exists():检查给定的键名是否存在于数组中( 参数1：键名 参数2：数组 ):返回bool值
$animals = array("a"=>"dog", "b"=>"cat", "c"=>"cow", "d"=>"horse","d"=>"lion");
echo array_key_exists("a",$animals); //1 没有不返回false值

$search_array = array('first' => 1, 'second' => 4);
if (array_key_exists('first', $search_array)) {
echo "The 'first' element is in the array";
} //The 'first' element is in the array

/* 数组指针操作 */

//key():返回数组内部指针当前指向元素的键名
//current():返回数组当前的元素
//next():把指向当前元素的指针移动到下一个元素的位置，并返回当前元素的值
//prev():把指向当前元素的指针移动到上一个元素的位置，并返回当前元素的值
//end():把当前内部指针指向最后一个元素，并返回该元素的值
//reset():把数组元素指针指向第一个值，并返回这个元素的值

$array = array(
'fruit1' => 'apple',
'fruit2' => 'orange',
'fruit3' => 'grape',
'fruit4' => 'apple',
'fruit5' => 'apple');

while ($fruit_name = current($array)) {
if ($fruit_name == 'apple') {
echo key($array).'<br />';
}
next($array);
} //fruit1 fruit4 fruit5

/* 遍历数组 */
/*正方向遍历*/
$a = array(10,20,30);
reset($a);
do{
echo key($a)."==>".current($a)."<br/>";
}while(next($a)); // 0==>10 1==>20 2==>30

/*倒向遍历*/
end($a);
do{
echo key($a)."===>".current($a)."<br/>";
}while(prev($a)); //2===>30 1===>20 0===>10

/* 指针 */
$transport = array('foot', 'bike', 'car', 'plane');
/*默认第一个为当前元素*/
$mode = current($transport); // $mode = 'foot';
$mode = next($transport); // $mode = 'bike';

/*当前元素为'bike'*/
$mode = current($transport); // $mode = 'bike';
$mode = prev($transport); // $mode = 'foot';
$mode = end($transport); // $mode = 'plane';
$mode = current($transport); // $mode = 'plane';

//list():把数组中的值赋给一些变量---------list不是函数
$arr = array("Cat","Dog","Horse","Cow");
list($a,$b,$c,$d) = $arr;
echo $a; //Cat
echo $b; //Dog
echo $c; //Horse
echo $d; //Cow

//array_shift():删除数组中的第一个元素，并返回被删除元素的值
$a = array("1"=>"Dog","2"=>"Cat","3"=>"Horse");
echo array_shift($a); //Dog
print_r ($a); //Array ( [b] => Cat [c] => Horse )

//array_unshift():在数组开关插入一个或多个元素(如果当前数组为索引数组，则从0开始，依此类推;关联数组键名不变)
$a = array("10"=>"Cat","b"=>"Dog",3=>"horse",5=>"lion");
array_unshift($a,"Horse");
print_r($a); //Array ( [0] => Horse [1] => Cat [b] => Dog [2] => horse [3] => lion )

//array_push():向数组最后压入一个或多个元素
$a=array("a"=>"Dog","3"=>"Cat");
array_push($a,"Horse","Bird");
print_r($a); //Array ( [a] => Dog [3] => Cat [4] => Horse [5] => Bird )

//array_pop():删除数组中的最后一个元素
$a=array("Dog","Cat","Horse");
array_pop($a);
print_r($a); //Array ( [0] => Dog [1] => Cat )

/* 数组键值操作 */
//shuffle():将数组打乱，键名为索引数组从0开始(不能直接打印shuffle，分开写)
$animals = array("a"=>"dog", "b"=>"cat", "c"=>"cow", "d"=>"horse","d"=>"lion");
shuffle($animals);
print_r($animals); //Array ( [0] => dog [1] => cow [2] => cat [3] => lion ) 每刷新一次会随机变化

//count():计算数组中的单元数目式对象中的属性个数
$people = array("Peter", "Joe", "Glenn", "Cleveland");
echo count($people); //4

//array_flip():返回一个键值反转后的数组
$a = array(0=>"Dog",1=>"Cat",2=>"Horse");
print_r(array_flip($a)); //Array ( [Dog] => 0 [Cat] => 1 [Horse] => 2 )

//array_keys():返回数组所有的键，组成一个数组
$a = array("a"=>"Horse","b"=>"Cat","c"=>"Dog");
print_r(array_keys($a)); //Array ( [0] => a [1] => b [2] => c )

//array_values():返回数组中所有的值，组成一个数组
$a = array("a"=>"Horse","b"=>"Cat","c"=>"Dog");
print_r(array_values($a)); //Array ( [0] => Horse [1] => Cat [2] => Dog )

//array_reverse():返回一个元素顺序相反的数组
$a = array("a"=>"Horse","b"=>"Cat","c"=>"Dog");
print_r(array_reverse($a)); //Array ( [c] => Dog [b] => Cat [a] => Horse )

//array_count_values():统计数组中所有值出现的次数
$a = array(1,2,3,4,1,1,3,5,3,2,1,3,4);
print_r(array_count_values($a)); //Array ( [1] => 4 [2] => 2 [3] => 4 [4] => 2 [5] => 1 )

//array_rand():从数组中随机抽取一个或多个元素，注意是键名
$a=array("a"=>"Dog","b"=>"Cat","c"=>"Horse","d"=>"Lion","e"=>"Cow");
print_r(array_rand($a,3)); //Array ( [0] => b [1] => c [2] => e ) ***随机***

//each():返回数组中当前的键／值对并将数组指针向后移动一步
$foo = array("bob", "fred", "jussi", "jouni", "egon", "marliese");
$bar = each($foo);
print_r($bar); //Array ( [1] => bob [value] => bob [0] => 0 [key] => 0 )

/*每遍历一次，指针向后移动一位*/
$bar = each($foo);
print_r($bar); //Array ( [1] => fred [value] => fred [0] => 1 [key] => 1 )

//array_unique():删除重复值，返回剩余数组
$a=array("a"=>"Dog","b"=>"Cat","c"=>"Horse","d"=>"Dog","e"=>"cow","f"=>"Cow");
print_r(array_unique($a)); //Array ( [a] => Dog [b] => Cat [c] => Horse [e] => cow [f] => Cow )

/* 数组排序 */
/**
* 返回值为1(正值)：表示交换顺序
* 返回值为－1(负值)：表示不交换顺序
**/

/**
* //原始键名被忽略(从零开始)(字符串顺序)
* sort():对值由小到大
* rsort():对值由大到小
*
* //原始键名保留(字符串顺序)
* asort():对值从小到大
* arsort():对值从大到小
**/
$my_array = array("a" => "Dog", "b" => "Cat", "c" => "Horse");
sort($my_array);
print_r($my_array); //Array ( [0] => Cat [1] => Dog [2] => Horse )

$my_array = array("a" => "Dog", "b" => "Cat", "c" => "Horse");
asort($my_array);
print_r($my_array); //Array ( [b] => Cat [a] => Dog [c] => Horse )

/**
* ksort():对下标由小到大
* krsort():对下标由大到小
**/
$my_array = array("h" => "Dog", "s" => "Cat", "a" => "Horse");
ksort($my_array);
print_r($my_array); //Array ( [a] => Horse [h] => Dog [s] => Cat )

$my_array = array("e" => "Dog", "2" => "Cat", "a" => "Horse");//按什么顺序排序
ksort($my_array);
print_r($my_array); //Array ( [a] => Horse [e] => Dog [2] => Cat )

/**
* usort():使用用户自定义的回调函数对数组排序
* uasort():使用用户自定义的回调函数对数组排序并保持索引关联
* uksort():使用用户自定义的回调函数对数组排序对数组键排序
**/
$v = array(1,3,5,2,4);
usort($v,'fun');
function fun($v1,$v2){
return ( $v1 > $v2 ) ? 1 : -1;
}
print_r($v); //Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => 5 )

/* 排序加遍历 */
function cmp($a, $b)
{
if ($a == $b) {
return 0;
}
return ($a < $b) ? -1 : 1;
}
$a = array(3, 2, 5, 6, 1);
usort($a, "cmp");
foreach ($a as $key => $value) {
echo $key."===>".$value." "; //0===>1 1===>2 2===>3 3===>5 4===>6
}

/* 排序遍历结束 */
/**
* sort():由小到大的字串排序（字母相等，比较不相等之后的一位大小）
* natsort();由小到大的自然排序（字母相等，比较数值）***区分大小写
* natcasesort():不区分大小写的自然排序
**/
$a = array("a" => "id2", "b" => "id12", "c" => "id22","d" => "ID22");
sort($a); print_r($a); //Array ( [0] => ID22 [1] => id12 [2] => id2 [3] => id22 )
natsort($a); print_r($a); //Array ( [0] => ID22 [2] => id2 [1] => id12 [3] => id22 )
natcasesort($a); print_r($a); //Array ( [2] => id2 [1] => id12 [3] => id22 [0] => ID22 )