php学习7——数组

创建数组

$my_arr=array();

$my_arr=array('a','b','c','d');

$my_arr=array(1,2,3,4);

$my_arr=array('a'=>'x1','b'=>'x2','c'=>'x3','d'=>'x4');

$str=range('a','z');
print_r ($str);

out：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 )

$str=range('a','z');
print_r ($str);

out：Array ( [0] => a [1] => c [2] => e [3] => g [4] => i [5] => k [6] => m [7] => o [8] => q [9] => s [10] => u [11] => w [12] => y )

$str=range(0,10 ,-2);
print_r ($str);

out：Array ( [0] => 0 [1] => 2 [2] => 4 [3] => 6 [4] => 8 [5] => 10 )

访问数组

$my_arr[0];
$my_arr['a'];

输出数组

print_r(array,true)

var_export(array,true)

var_dump(array)

数组输出为字符串（两个函数是相同的互为别名）

implode(', ',array);

join(', ',array);

ex

$my_arr=array('a','b','c','d');
$str=implode('-',$my_arr);
echo $str;

out：a-b-c-d

$my_arr=array('a'=>'x1','b'=>'x2','c'=>'x3','d'=>'x4');
$str=implode('-',$my_arr);
echo $str;

 out：x1-x2-x3-x4

只输出值或键

array_values(array)//把数组中的值输出为字符串

array_keys(array)//把数组中的键输出为字符串

数组追加

array_merge($arr,$arr2,……)

$my_arr1=array('a','b','c','d');

$my_arr2=array(1,2,3,4);

$my_arr3=array('a'=>'x1','b'=>'x2','c'=>'x3','d'=>'x4');
$new_arr=array_merge($my_arr1,$my_arr2);
$new_arr2=array_merge($my_arr1,$my_arr2,$my_arr3);
print_r( $new_arr) ;
print_r($new_arr2);

out：Array ( [0] => a [1] => b [2] => c [3] => d [4] => 1 [5] => 2 [6] => 3 [7] => 4 )

Array ( [0] => a [1] => b [2] => c [3] => d [4] => 1 [5] => 2 [6] => 3 [7] => 4 [a] => x1 [b] => x2 [c] => x3 [d] => x4 )

数组元素统计

count()=sizeof();

删除数组指定的元素，第一个元素和最后一个元素（栈和队列）

unset($array['key'])

array_shift(array)

array_pop(array)

删除一个或多个数组元素

array_splice(array,start,length)

array_slice(array,start,length)

查找

in_array($str,array) 返回bool值，存在返回true，否则返回false

array_key_exists($key,array)

数组处理

max(array),

min(array),

array_sum(array)

回调函数

array_walk(array,funcname)//会修改原数组

array_map(funcname,array)//不会修改原数组

array_filter(array,funcname)//