lua學習之table型別
阿新 • • 發佈：2019-01-03
關係表型別，這是一個很強大的型別。我們可以把這個型別看作是一個數組。只是C語言的陣列，只能用正整數來作索引； 在Lua中，你可以用任意型別的值來作陣列的索引，但這個值不能是nil。同樣，在C語言中，陣列的內容只允許一種型別；在Lua中，你也可以用任意型別的值來作陣列的內容，nil也可以。
基本介紹
注意三點： 第一，所有元素之間，總是用逗號 "，" 隔開； 第二，所有索引值都需要用 "["和"]" 括起來；如果是字串，還可以去掉引號和中括號； 即如果沒有[]括起，則認為是字串索引 第三，如果不寫索引，則索引就會被認為是數字，並按順序自動從 1往後編； 例如： tt = {
--note: the more closures made, the slower the program would run. function mg1( n) local function get () return n ; end local function inc (m ) n = n +m ; end return {get = get, inc= inc} end object = mg1(50 ) print(object.get ()) print(object["get" ]()) object.inc(2 ) print(object.get ()) ---------------------------------------- do local function get (o )
注意三點： 第一，所有元素之間，總是用逗號 "，" 隔開； 第二，所有索引值都需要用 "["和"]" 括起來；如果是字串，還可以去掉引號和中括號； 即如果沒有[]括起，則認為是字串索引 第三，如果不寫索引，則索引就會被認為是數字，並按順序自動從 1往後編； 例如： tt = {
table[1] to table[n], where n is the length of the table. If comp is given, then it must be a function that
receives two table elements, and returns true when the first is less than the second (so that not comp(a[i+1],a[i]) will be true after the sort). If comp is not given, then the standard Lua operator < is used instead.
The sort algorithm is not stable; that is, elements considered equal by the given order may have their relative positions changed by the sort.
name = {"you" ,"me", "him","bill" } --table.sort - only works with arrays! table.sort(name) for k, v in ipairs( name) do print( k,v) end --table.sort uses callbacks. a function that is writtent to be called by a library function. function cmp( a, b) if string.sub(a,2 ,2) < string.sub(b,2 ,2) then return true else return false end end table.sort(name, cmp) for k, v in ipairs( name) do print( k,v) end Inserts elementvalue at position pos in table, shifting up other elements to open space, if necessary. The default value for pos is n+1,
where n is the length of the table so that a call table.insert(t,x) inserts x at the end of table t.
--table.insert --an easy to copy a table to another table or adding elements to an array.!
foo = {"a" ,"c", "d"}
bar = {}
function printt( table)
for i=1 ,#table do
print(i,table [i ])
end
end
print("before
insert:" )
printt(foo)
table.insert(foo,2 ,"b")
print("after
insert" )
printt(foo)
Given an array where all elements are strings or numbers, returns table[i]..sep..table[i+1] ··· sep..table[j]. The default value for sep is the empty string, the default for i is 1, and the default for j is
the length of the table. If i is greater than j, returns the empty string.
--table.concat does what it implies. Takes an array and concates to one string.
num = {1 ,2, 3,4,5 ,6}
print(table.concat (num ,"<"))
Removes from table the element at position pos, shifting down other elements to close the space, if necessary. Returns the value of the removed element. The default value for pos is n, where n is
the length of the table, so that a call table.remove(t) removes the last element of table t.
Returns the largest positive numerical index of the given table, or zero if the table has no positive numerical indices. (To do its job this function does a linear traversal of the whole table.)
--table.maxn apple = {"a" ,"p",[ 5]="e"} print(table.maxn (apple )) -- 5 duck = {[-2 ]=3,[- 1]=0} print(table.maxn (duck )) -- 0 面向物件程式設計 --note for a object to work, it needs a closure(inner function with an upvalue(a local value from a higher scope))--note: the more closures made, the slower the program would run. function mg1( n) local function get () return n ; end local function inc (m ) n = n +m ; end return {get = get, inc= inc} end object = mg1(50 ) print(object.get ()) print(object["get" ]()) object.inc(2 ) print(object.get ()) ---------------------------------------- do local function get (o )