Control Structure Tutorial
Lua control structures will be familiar to programmers. Sections 2.4.4 and 2.4.5 of the Reference Manual provide the necessary information.
while
The conditional looping statement "while
" has the form:
while
exp do
block end
A simple loop:
We can exit the control of a while statement using the break keyword as in the following example.
repeat
The conditional looping statement "repeat
" has the form:
repeat
block until
exp
A simple loop:
Like the while statement, we can exit a repeat loop using a break statement:
cows_come_home is a variable which is not defined. When we access it we get the value nil, so this code means "until false" or forever.
for
The iterating statement "for
" has two forms. The first is "for
" numerical iteration:
The second is for sequential iteration, e.g. to print the contents of a table. In the example below, 'for' is passed the 'pairs()' iterator function, whose purpose is to supply the values of each iteration:
if ... then ... else ... end
The statement "if
" has the form:
if
exp then
block { elseif
exp then
block } [ else
block ] end
For example,if
... then
... end
if
... then
... else
... end
if
... then
... elseif
... else
... end