Lua程序设计第4版第8章课后练习答案

8.1
没有switch，elseif比使用多个if性能更高

8.2
while(true)
for 1,math.huge
repeat
goto

8.3
你想怎样都好

8.4

function room1()
    local move = io.read()
    if move == "south" then
        room3()
    elseif move == "east" then
        room2()
    else
        print("invalid move")
        room1()
    end
end
function room2()
    local move = io.read()
    if move == "south" then
        room4()
    elseif move == "west" then
        room1()
    else
        print("invalid move")
        room2()
    end
end
function room3()
    local move = io.read()
    if move == "north" then
        room1()
    elseif move == "east" then
        room4()
    else
        print("invalid move")
        room3()
    end
end
function room4()
    print("congratulations , you won!")
end

room1()

8.5
假如goto语句能跳出函数，直接跳转到某个变量的作用域，却绕过了变量的声明与赋值，会发生无法预料的错误，本来局部的变成使用全局的人也可能

8.6
原理同上