onetoten = range(1,11) for count in onetoten: print count
1 2 3 4 5 6 7 8 9 10
for count in range(1,11): print count
>>> range(1,10) [1, 2, 3, 4, 5, 6, 7, 8, 9] >>> range(-32, -20) [-32, -31, -30, -29, -28, -27, -26, -25, -24, -23, -22, -21] >>> range(5,21) [5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20] >>> range(21,5) []
for count in onetoten:
uses the for control structure. A for control structure looks like for variable in list:. list is gone through starting with the first element of the list and going to the last. As for goes through each element in a list it puts each into variable. That allows variable to be used in each successive time the for loop is run through. Here is another example (you don't have to type this) to demonstrate:
demolist = ['life',42, 'the universe', 6,'and',7,'everything'] for item in demolist: print "The Current item is:", print item
The Current item is: life The Current item is: 42 The Current item is: the universe The Current item is: 6 The Current item is: and The Current item is: 7 The Current item is: everything
l = [2,4,6,8] sum = 0 for num in l: sum = sum + num print "The sum is: ",sum
The sum is: 20
l = [4, 5, 7, 8, 9, 1,0,7,10] l.sort() prev = l[0] del l[0] for item in l: if prev == item: print "Duplicate of ",prev," Found" prev = item
Duplicate of 7 Found
l = [4, 5, 7, 8, 9, 1,0,7,10] print "l = [4, 5, 7, 8, 9, 1,0,7,10]","\tl:",l l.sort() print "l.sort()","\tl:",l prev = l[0] print "prev = l[0]","\tprev:",prev del l[0] print "del l[0]","\tl:",l for item in l: if prev == item: print "Duplicate of ",prev," Found" print "if prev == item:","\tprev:",prev,"\titem:",item prev = item print "prev = item","\t\tprev:",prev,"\titem:",item
l = [4, 5, 7, 8, 9, 1,0,7,10] l: [4, 5, 7, 8, 9, 1, 0, 7, 10] l.sort() l: [0, 1, 4, 5, 7, 7, 8, 9, 10] prev = l[0] prev: 0 del l[0] l: [1, 4, 5, 7, 7, 8, 9, 10] if prev == item: prev: 0 item: 1 prev = item prev: 1 item: 1 if prev == item: prev: 1 item: 4 prev = item prev: 4 item: 4 if prev == item: prev: 4 item: 5 prev = item prev: 5 item: 5 if prev == item: prev: 5 item: 7 prev = item prev: 7 item: 7 Duplicate of 7 Found if prev == item: prev: 7 item: 7 prev = item prev: 7 item: 7 if prev == item: prev: 7 item: 8 prev = item prev: 8 item: 8 if prev == item: prev: 8 item: 9 prev = item prev: 9 item: 9 if prev == item: prev: 9 item: 10 prev = item prev: 10 item: 10
\t
is used to print a tab.)
The other way to use for loops is to do something a certain number of times. Here is some code to print out the first 11 numbers of the Fibonacci series:
a = 1 b = 1 for c in range(1,10): print a, n = a + b a = b b = n
1 1 2 3 5 8 13 21 34