Repeat

repeat
  line of code
  line of code
until expr

repeat allows you to repeat a block of lines until a condition is fullfilled, in other words until the expression after 'until' is not zero.
All repeat loops are run at least once.
Two other statements can be used inside all loops:
- break; to exit from a loop (example 2)
- continue; to interrupt the current iteration and start over from the begining of the loop. (example 3)
Loops of any kind can be nested, but not intertwined.

Correct:

for i=1 to 5
repeat
..
..
until a = "" $
end for

Incorrect:

for i=1 to 5
repeat
..
..
end for
until a = "" $

Example 1:
(A classic mistake is to forget to increment the control variable, something that is done automatically by the for loop)

rem Table of 4
i = 1
repeat
print(int(i)$, "* 4 = ", i * 4, "\n")
i = i + 1
until i = 5

1 * 4 = 4.0000
2 * 4 = 8.0000
3 * 4 = 12.0000
4 * 4 = 16.0000

Example 2:

k = 1
repeat
print(k, "\n")
if k = 3
break
end if
k = k + 1
until k = 10

1
2
3

Example 3:

l = 0
repeat
l = l + 1
if l = 2
continue
end if
print(l, "\n")

until l > 4

1
3
4
5