【perl】列表，陣列和雜湊的巢狀
Ⅰ. 列表巢狀列表（列表巢狀列表即為二維列表）
a. 列表的宣告
方法一：
@list = (
["banana","apple","orange","pear"],
["cauliflower","lettuce","tomato","cucumber"],
["orange juice","apple juice","red tea","red wine"]
);
方法二：
@fruit = ("banana","apple","orange","pear"); @vegetable = ("cauliflower","lettuce","tomato","cucumber"); @drink = ("orange juice","apple juice","red tea","red wine");
正確方法：
@list = ([@fruit],[@vegetable],[@drink]);錯誤方法：
@list = (@fruit, @vegetable, @drink);錯誤剖析：如果不用[]把每個子列表括起來，那麼這個列表@list就相當於@fruit, @vegetable, @drink這三個列表拼接而成的一個一維列表相當於@list = ("banana","apple","orange","pear","cauliflower","lettuce","tomato","cucumber","orange juice","apple juice","red tea","red wine")
方法三：
正確方法：
$list[0] = ["banana","apple","orange","pear"];錯誤方法：
$list[0] = ("banana","apple","orange","pear");錯誤剖析：這樣的結果是$list[0] = "pear" 並且會報警告
b. 列表的訪問
$list[0][0] = "banana";
#$list[0] and @list[0] 兩種表示都可以，但是 @list[0] 會報警告
Ⅱ. 列表巢狀雜湊
a. 列表的宣告
方法一：
@list = (
{
'fruit' => 'banana',
'vegetable' => 'cauliflower',
'drink' => 'orange juice'
},
{
'fruit' => 'apple',
'vegetable' => 'lettuce',
'drink' => 'apple juice'
},
{
'fruit' => 'orange',
'vegetable' => 'tomato',
'drink' => 'red tea'
},
{
'fruit' => 'pear',
'vegetable' => 'cucumber',
'drink' => 'red wine'
}
);
方法二：
%group1 = (
'fruit' => 'banana',
'vegetable' => 'cauliflower',
'drink' => 'orange juice'
);
%group2 = (
'fruit' => 'apple',
'vegetable' => 'lettuce',
'drink' => 'apple juice'
);
%group3 = (
'fruit' => 'orange',
'vegetable' => 'tomato',
'drink' => 'red tea'
);
%group4 = (
'fruit' => 'pear',
'vegetable' => 'cucumber',
'drink' => 'red wine'
);
正確方法：
@list = ({%group1}, {%group2}, {%group3}, {%group4});錯誤方法：
@list = (%group1, %group2, %group3, %group4);錯誤剖析：如果不用{}把每個子列表括起來，那麼這個列表@list就相當於%group1, %group2, %group3, %group4 這四個雜湊拼接而成的一個一維列表，相當於@list = ( 'fruit', 'banana', 'drink', 'orange juice', 'vegetable', 'cauliflower', 'fruit', 'apple', 'drink', 'apple juice', 'vegetable', 'lettuce', 'fruit', 'orange', 'drink', 'red tea', 'vegetable', 'tomato', 'fruit', 'pear', 'drink', 'red wine', 'vegetable', 'cucumber')
方法三：
正確方法：
$list[0] = {'fruit' => 'banana', 'vegetable' => 'cauliflower','drink' => 'orange juice'};
$list[0] = {%group1};錯誤方法：
$list[0] = ('fruit' => 'banana', 'vegetable' => 'cauliflower','drink' => 'orange juice');錯誤剖析：這樣的結果是$list[0] = 'orange juice' 並且有警告
$list[0] = ['fruit' => 'banana', 'vegetable' => 'cauliflower','drink' => 'orange juice']
錯誤剖析：這樣的結果是$list[0] = ['fruit','banana','vegetable','cauliflower','drink','orange juice']
b. 列表的訪問
$list[0]{'fruit'} = 'banana' ;
$list[0]{fruit}= 'banana'; #兩者都可以
$list[0] = {'fruit' => 'banana','drink' => 'orange juice','vegetable' => 'cauliflower'}；
Ⅲ. 雜湊巢狀雜湊
a. 雜湊的宣告
方法一：
my %hash = (
group1 => {
'fruit' => 'banana',
'vegetable' => 'cauliflower',
'drink' => 'orange juice'
},
group2 => {
fruit => 'apple',
vegetable => 'lettuce',
drink => 'apple juice'
},
group3 => {
'fruit' => 'orange',
'vegetable' => 'tomato',
'drink' => 'red tea'
},
group4 => {
fruit => 'pear',
vegetable => 'cucumber',
drink => 'red wine'
}
);%hash = (
'group1', {'fruit', 'banana', 'drink', 'orange juice', 'vegetable', 'cauliflower'},
'group2', {'fruit', 'apple', 'drink', 'apple juice', 'vegetable', 'lettuce'},
'group3', {'fruit', 'orange', 'drink', 'red tea', 'vegetable', 'tomato'},
'group4', {'fruit', 'pear', 'drink', 'red wine', 'vegetable', 'cucumber'}
);
方法二：
%group1 = (
'fruit' => 'banana',
'vegetable' => 'cauliflower',
'drink' => 'orange juice'
);
%group2 = (
'fruit' => 'apple',
'vegetable' => 'lettuce',
'drink' => 'apple juice'
);
%group3 = (
'fruit' => 'orange',
'vegetable' => 'tomato',
'drink' => 'red tea'
);
%group4 = (
'fruit' => 'pear',
'vegetable' => 'cucumber',
'drink' => 'red wine'
);
正確方法：
%hash = (
'group1' => {%group1},
'group2' => {%group2},
'group3' => {%group3},
'group4' => {%group4}
);錯誤方法：
%hash = (%group1, %group2, %group3, %group4); 錯誤剖析：這個雜湊相當於%hash = %group4
%hash = (
'group1' => %group1,
'group2' => %group2,
'group3' => %group3,
'group4' => %group4
);
錯誤剖析：這個雜湊的結果相當於 %hash = ('tomato','group4','orange juice','vegetable','cauliflower','group2','orange','drink','fruit','pear','group1','fruit','banana','drink','drink','red wine','vegetable','cucumber','group3','fruit','red tea','vegetable')
方法三：
$hash{group1} = {%group1};
$hash{'group1'} = {
'fruit' => 'banana',
'vegetable' => 'cauliflower',
'drink' => 'orange juice'
};
$hash{'group1'} = {'fruit', 'banana', 'vegetable', 'cauliflower', 'drink', 'orange juice'};b. 雜湊的訪問
$hash{'group1'}{'fruit'} = 'banana' and $hash{group1}{fruit} are the same.
$list{group1) = {'fruit' => 'banana','drink' => 'orange juice','vegetable' => 'cauliflower'}；
Ⅳ. 雜湊巢狀列表
a. 雜湊的宣告
方法一：
%hash = (
'fruit' => ["banana","apple","orange","pear"],
'vegetable' => ["cauliflower","lettuce","tomato","cucumber"],
'drink' => ["orange juice","apple juice","red tea","red wine"]
);
%hash = (
'fruit', ["banana","apple","orange","pear"],
'vegetable', ["cauliflower","lettuce","tomato","cucumber"],
'drink', ["orange juice","apple juice","red tea","red wine"]
);
方法二：
@fruit = ("banana","apple","orange","pear")；
@vegetable = ("cauliflower","lettuce","tomato","cucumber")；
@drink = ("orange juice","apple juice","red tea","red wine")；
%hash = (
'fruit', [@fruit],
'vegetable', [@vegetable],
'drink', [@vegetable]
);
方法三：
$hash{fruit} = [@fruit]；
$hash{'fruit'} = ["banana","apple","orange","pear"]；
b. 雜湊的訪問
$hash{'fruit'}[0] = 'banana';
$hash{'fruit'} = ['banana','apple','orange','pear'];