lua 常用函数思路

1、计算数字位数，前位补零

-- 计算数字的位数
function DightNum(num)
    if math.floor(num) ~= num or num < 0 then
        return -1
    elseif 0 == num then
        return 1
    else
        local tmp_dight = 0
        while num > 0 do
            num = math.floor(num/10)
            tmp_dight = tmp_dight + 1
        end
        return tmp_dight 
    end
end

-- 在整数数字前面加0，例：3 变成 "03"
-- local a = 3
-- local s = AddZeroFrontNum(2,a)
-- 那么s是"03"
function AddZeroFrontNum(dest_dight, num)
    local num_dight = DightNum(num)
    if -1 == num_dight then 
        return -1 
    elseif num_dight >= dest_dight then
        return tostring(num)
    else
        local str_e = ""
        for var =1, dest_dight - num_dight do
            str_e = str_e .. "0"
        end
        return str_e .. tostring(num)
    end
end

2、时间戳格式化

function ShortTime(difftime)                  --时间格式化 00：00：00
    local hour = math.floor(difftime / (60 * 60) % 24);
    local minute = math.floor(difftime / 60 % 60);
    local sec = math.floor(difftime % 60)
    local timeStr;
    if hour < 10 then
        hour = "0" .. hour
    end
    if minute < 10 then
        minute = "0" .. minute
    end
    if sec < 10 then
        sec = "0" .. sec
    end
    timeStr = hour .. ":" .. minute .. ":" .. sec--string.format("%s:%s:%s", hour, minute, sec);
    return timeStr;
end

3、贝塞尔曲线（3点定一曲线）

function BezierLineSecondOrder()                --2阶贝塞尔曲线(3点定一曲线)
    this.points = {}
    local p1 = Vector3.New(600,600,0)            --起点
    local p2 = Vector3.New(1000,300,0)           --作用点
    local p3 = Vector3.New(0,0,0)                --终点
    local t = 80                                 --插值（0~1）
    for i = 1, 200 do                            --生成点阵
        local v1 = Vector3.Lerp(p1,p2,i/t)
        local v2 = Vector3.Lerp(p2,p3,i/t)
        local find = Vector3.Lerp(v1,v2,i/t)
        table.insert(this.points,find)
    end
end

4、lua 值类型判断

function ValueType(v)
    local typ = type(v)
    if typ == "string" then
        return VT.STR
    elseif typ == "table" then
        return VT.TAB
    elseif typ == "boolean" then
        return VT.BOOL
    elseif typ == "number" then
        local n, f = math.modf(v)
        if f > 0 then
            return VT.F32
        elseif v >= -128 and v <= 127 then
            return VT.S8
        elseif v >= -32768 and v <= 32767 then
            return VT.S16
        elseif v >= -2147483648 and v <= 2147483647 then
            return VT.S32
        else
            return VT.S64
        end
    end
end

5、io

function writefile(path, content, mode)
    mode = mode or "w+b"
    local file = io.open(path, mode)
    if file then
        if file:write(content) == nil then return false end
        io.close(file)
        return true
    else
        return false
    end
end

function exists(path)
    local file = io.open(path, "r")
    if file then
        io.close(file)
        return true
    end
    return false
end

function readfile(path)
    local file = io.open(path, "r")
    if file then
        local content = file:read("*a")
        io.close(file)
        return content
    end
    return nil
end

6、数字缩写

--格式化数字表现(超过万的过滤掉)
function SpeFormatNumberToStr(num)
    if num < 100000 then
        return tostring(num);
    end

    local myraid = math.floor(num / 10000);
    local remain = math.floor(num % 10000);
    if remain <= 0 then
        remain = "";
    end
    if myraid >= 10000 then
        local upVal = math.floor(myraid / 10000);
        local remainMyraid = math.floor(myraid % 10000);
        if remainMyraid <= 0 then
            return string.format("%d亿", upVal);
        end
        return string.format("%d亿%d万", upVal, remainMyraid);
    end

    return string.format("%d万", myraid);
end

7、时间

--将时间转化为年月日
function FormatTimeToDate(time)
    local CurYear = os.date("%Y", time);
    local CurMon = os.date("%m", time);
    local CurDay = os.date("%d", time);
    return string.format("%d-%02d-%d", CurYear, CurMon, CurDay)
end

--时间转时间戳
function FormatTime(time, hour, min, sec, nextday)
    local CurYear = os.date("%Y", time);
    local CurMon = os.date("%m", time);
    local CurDay = os.date("%d", time);
    if nextday then
        CurDay = CurDay + 1;
    end
    local CurSec = sec or os.date("%S", time);
    return os.time({ year = CurYear, month = CurMon, day = CurDay, hour = hour, min = min, sec = CurSec})
end

8、tolua关于update函数使用，具体函数实现原理在LuaBeatEvent C#类中，关联event lua类中

UpdateBeat:Add(UpdateLoop)
UpdateBeat:Remove(UpdateLoop)