FOR
===

Function
--------

**FOR** executes a series of instructions in a loop a given number of
times.

Syntax
------

| FOR N = A TO B STEP C
| NEXT N

Where N is a variable, A is a numeric start value, B is a numeric end
value and C is an increment/decrement value.

A, B and C can be numbers, variables or expressions.

Examples
--------

::

   10 FOR A = 1 TO 100 STEP 10
   100 NEXT A

causes the value of A to equal 1,11,21 etc., for each execution of the
loop.

To obtain a decrementing count negative values of STEP are used.

::

   1000 FOR Z1=91 TO 10 STEP -.1
   1050 NEXT Z1

Remarks
-------

When followed by a :doc:`next` statement, FOR will execute the
intervening parameters for the number of times indicated by the values A
and B divided by N to the formula:

(B-A+2)/N

When terminating F0R...NEXT loops it is important to end using NEXT and
not :doc:`goto`. Alternatively, exiting via a
:doc:`return` when in a subroutine will not cause a build up of
the 'control stack'.

Failure to do this will result in a control stack error.