Lua Study Notes 11: Tips in lua, lua Study Notes

Lua Study Notes 11: Tips in lua, lua Study Notes

The tips in lua are the special features of the basic lua language.

Clever Use or

 x = x or v

It is equivalent:

if not x then    x = vend

If x is nil or false, assign it a value

Binary ternary operator implementation

a and b or c

Similar to C language:

a ? b : c

The and operation takes precedence over or.

Fill in 0 for the third digit

str = string.format("%02d",num)

Equivalent

if num < 10 then    str = string.format("0%d", num)else    str = string.format("%d", num)end

This expression is often used to get regular image names, time conversion, etc.

Assignment Problem and type method in lua

The print (123) function is used to output information to the standard. Print does not return values.
So your a = print (123)
No effect on. It still does not exist. Read any nonexistent variable to obtain nil.
If the type parameter is nil, nil is returned. So type (a) = type (nil) = nil
Degrees for type (a) will return nil, nil is lua built-in type, indicating that the value does not exist.

How LUA cainiao installed LUA

In windows, you don't have to worry about using the compiled installation package:
Luaforge.net/frs /? Group_id = 377