php定义二维数组从PHP开端学渗入渗出数组

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一、把多个数据放到一个变量里面的凑集叫做数组

二、数组分类

php定义二维数组从PHP开端学渗入渗出数组 Python

1、索引数组，以下标取值

<?php$a = array('1',2,3,'324');echo "$a[2]";echo " ";echo "$a[3]";echo " ";var_dump($a[2]);echo " ";var_dump($a[3]);?>运行结果：3324int(3)string(3) "324"

<?php$a[] = '1';$a[] = 123;$a[] = '123';$a[] = 456;echo "$a[2]";echo " ";echo "$a[3]";echo " ";var_dump($a[2]);echo " ";var_dump($a);echo " ";print_r($a);?>运行结果：123456string(3) "123"array(4) { [0]=> string(1) "1" [1]=> int(123) [2]=> string(3) "123" [3]=> int(456) }Array ( [0] => 1 [1] => 123 [2] => 123 [3] => 456 )

2、关联索引，自定义下标，下标必须用单引号

<?php$a = array('a'=>'1','b'=>2,'c'=>3,'d'=>'324');echo "$a[a]";echo " ";echo "$a[c]";echo " ";var_dump($a[a]);echo " ";var_dump($a[d]);?>运行结果：13string(1) "1"string(3) "324"

3、遍历普通数组，count函数打算数组个数

<?php$a = array('1',2,3,'324');for ($i=0; $i <count($a) ; $i++){echo "$a[$i]"." ";}?>4、遍历关联数组<?php$a = array('a'=>'1','b'=>2,'c'=>3,'d'=>'324');foreach ($a as $key => $value) {echo "$a[$key] ";}?>

4、二维数组

<?php$a = array(1,2,3,array('a','b','c'));foreach ($a as $key => $value) {if(is_array($value)){foreach ($value as $k => $v) {echo "$v"." "; } }else{echo "$value"." "; }}?>

禁止造孽，后果自大