Python has if, for, and while control statements. The for statement is
different than that in most other languages; it is more like the
foreach
loop in csh
. It takes the following form:
The loop body is executed with a new value for the variable item
for each iteration. The values are taken from a sequence-like object
(such as a string, list, or tuple ... but other possibilities exist),
and item
is set to each of the values in the sequence.
Note the colon after the statement - all statements that control the execution of a following block of statements (including for, if, while, etc.) end with a colon.
To get the common loop over consecutive integers, use the built-in
range
function:
range(100)
constructs a list of values from 0 to 99 (yes, 99!)
and the for loop repeats 100 times with values of i
starting
at 0 and ending at 99. The argument to range
is the number
of elements in the returned list, not the maximum value. There are
additional arguments to range
if you want a loop that starts
at a value other than zero or that increments by a value other than 1.
Questions or comments? Contact help@stsci.edu Documented updated on 2004 Jun 1 |