Lua语言中switch语句的替代方法是什么？

Question

我在C++中有这段代码,我想知道如何编写一些替换Lua中的switch语句的代码,因为我遇到了很多问题,我需要使用这个语句.

   int choice;
do// loop
{
      cout<<"\n >>> The General Menu <<< \n";
      cout << endl;
    cout<< " press (1) to Add    "<<endl;
    cout<< " press (2) to Save   "<<endl;
    cout<< " press (3) to Quit " << endl;
    cout<< endl;
      cout<< "Enter your choice please (1/2/3): ";
    cin>>choice;

    switch(choice)
    {
        case 1: 
            add();
            break;
        case 2:
            save();
            break;

        default:
            cout<<" The program has been terminated "<<endl;
           cout<<" Thank you! \n";          
    }   
} while (choice != 3);

该语句已在do..while循环中使用.

Answer 1

一般来说,如果你想在Lua中使用switch语句,你应该做的是构建一个表.对于简单的情况choice,可能是1,2或失败,if只需几个条件的简单语句就足够了.对于更复杂的情况,应使用函数表:

local c_tbl =
{
  [1] = add,
  [2] = save,
}

local func = c_tbl[choice]
if(func) then
  func()
else
  print " The program has been terminated."
  print " Thank you!";
end

您可以使用词法作用域来允许表中的函数能够访问局部变量,就像代码是内联编写的一样.

Answer 2

试试这个（单击此处在 Lua 编译器中运行脚本），希望代码是不言自明的;-) 和

类似于相同的伪代码格式..!!

print("enter your choice : ")
mychoice = io.read()

switch = function (choice)
  -- accepts both number as well as string
  choice = choice and tonumber(choice) or choice     -- returns a number if the choic is a number or string. 

  -- Define your cases
  case =
   {
     [1] = function ( )                              -- case 1 : 
             print("your choice is Number 1 ")       -- code block
     end,                                            -- break statement

     add = function ( )                              -- case 'add' : 
             print("your choice is string add ")     -- code block
     end,                                            -- break statement

    ['+'] = function ( )                             -- case '+' : 
             print("your choice is char + ")         -- code block
     end,                                            -- break statement

     default = function ( )                          -- default case
             print(" your choice is din't match any of those specified cases")   
     end,                                            -- u cant exclude end hear :-P
   }

  -- execution section
  if case[choice] then
     case[choice]()
  else
     case["default"]()
  end

end
-- Now you can use it as a regular function. Tadaaa..!!
switch(mychoice)

Answer 3

路亚：

if choice == 1
then add()
elseif choice == 2
then save()
else print "The program has been terminated\nThank you!"
end