PHP中的数组（拆分与合并）
explode
使用一个字符串分割另一个字符串
$str = "11,22,33";
$arr = explode(",",$str);
print_r($arr);
Array
(
[0] => 11
[1] => 22
[2] => 33
)implode
将一个一维数组的值转化为字符串
$arr = [11,22,33];
$str = implode("#",$arr);
echo $str;
11#22#33split
用正则表达式将字符串分割到数组中
preg_split()函数使用了Perl兼容正则表达式语法，通常是比split()更快的替代方案。如果不需要正则表达式的威力，则使用explode()更快，这样就不会招致正则表达式引擎的浪费。
该函数在PHP7中已被废弃
$str = "123dqaw76eqwv8902fwer12356";
$arr = split("[a-z]+", $str);
print_r($arr);
Array
(
[0] => 123
[1] => 76
[2] => 8902
[3] => 12356
)preg_split
通过一个正则表达式分隔字符串
如果你不需要正则表达式功能，可以有更快(并且更简单)的选择比如 explode() 或 str_split()。
如果没有成功匹配，将会返回一个数组，包含了单个元素，即输入的字符串。
$str = "123dqaw76eqwv8902fwer12356";
$arr = preg_split("/[a-z]+/i", $str);
print_r($arr);
Array
(
[0] => 123
[1] => 76
[2] => 8902
[3] => 12356
)str_split
将字符串转换为数组
$str = "hello world";
print_r(str_split($str));
print_r(str_split($str, 3));
Array
(
[0] => h
[1] => e
[2] => l
[3] => l
[4] => o
[5] =>
[6] => w
[7] => o
[8] => r
[9] => l
[10] => d
)
Array
(
[0] => hel
[1] => lo
[2] => wor
[3] => ld
)array_chunk
将一个数组分割成多个
$input_array = array('a', 'b', 'c', 'd', 'e');
print_r(array_chunk($input_array, 2));
print_r(array_chunk($input_array, 2, true));
Array
(
[0] => Array
(
[0] => a
[1] => b
)
[1] => Array
(
[0] => c
[1] => d
)
[2] => Array
(
[0] => e
)
)
Array
(
[0] => Array
(
[0] => a
[1] => b
)
[1] => Array
(
[2] => c
[3] => d
)
[2] => Array
(
[4] => e
)
)array_combine
创建一个数组，用一个数组的值作为其键名，另一个数组的值作为其值
$a = array('green', 'red', 'yellow');
$b = array('avocado', 'apple', 'banana');
$c = array_combine($a, $b);
print_r($c);
Array
(
[green] => avocado
[red] => apple
[yellow] => banana
)array_merge
合并一个或多个数组。一个数组中的值附加在前一个数组的后面，返回作为结果的数组。
别忘了数字键名将会被重新编号！
$array1 = array("color" => "red", 2, 4);
$array2 = array("a", "b", "color" => "green", "shape" => "trapezoid", 4);
$result = array_merge($array1, $array2);
print_r($result);
Array
(
[color] => red
[0] => 2
[1] => 4
)
Array
(
[0] => a
[1] => b
[color] => green
[shape] => trapezoid
[2] => 4
)
Array
(
[color] => green
[0] => 2
[1] => 4
[2] => a
[3] => b
[shape] => trapezoid
[4] => 4
)如果你想完全保留原有数组并只想新的数组附加到后面，用 + 运算符。如果两个被合并的数组含有相同的key，则保留第一个，忽略后边的。
$array1 = array(0 => 'zero_a', 2 => 'two_a', 3 => 'three_a');
$array2 = array(1 => 'one_b', 3 => 'three_b', 4 => 'four_b');
$result = $array1 + $array2;
print_r($result);
Array
(
[0] => zero_a
[2] => two_a
[3] => three_a
[1] => one_b
[4] => four_b
)array_merge_recursive
递归地合并一个或多个数组
如果输入的数组中有相同的字符串键名，则这些值会被合并到一个数组中去，这将递归下去，因此如果一个值本身是一个数组，本函数将按照相应的条目把它合并为另一个数组。然而，如果数组具有相同的数组键名，后一个值将不会覆盖原来的值，而是附加到后面。
$ar1 = array("color" => array("favorite" => "red"), 5);
$ar2 = array(10, "color" => array("favorite" => "green", "blue"));
$result = array_merge_recursive($ar1, $ar2);
print_r($ar1);
print_r($ar2);
print_r($result);
Array
(
[color] => Array
(
[favorite] => red
)
[0] => 5
)
Array
(
[0] => 10
[color] => Array
(
[favorite] => green
[0] => blue
)
)
Array
(
[color] => Array
(
[favorite] => Array
(
[0] => red
[1] => green
)
[0] => blue
)
[0] => 5
[1] => 10
)compact
建立一个数组，包括变量名和它们的值
对每个参数，compact() 在当前的符号表中查找该变量名并将它添加到输出的数组中，变量名成为键名而变量的内容成为该键的值。
任何没有变量名与之对应的字符串都被略过。
$city = "San Francisco";
$state = "CA";
$event = "SIGGRAPH";
$location_vars = array("city", "state");
$result = compact("event", "nothing_here", $location_vars);
print_r($result);
Array
(
[event] => SIGGRAPH
[city] => San Francisco
[state] => CA
)extract
从数组中将变量导入到当前的符号表
检查每个键名看是否可以作为一个合法的变量名，同时也检查和符号表中已有的变量名的冲突。
返回成功导入到符号表中的变量数目。
$var_array = [
"color" => "blue",
"size" => "medium",
"shape" => "sphere"
];
extract($var_array);
echo "$color, $size, $shape\n";
blue, medium, sphere参考
- PHP手册