Looping 1-10 PRINT either only EVEN, only ODDS, or ALL

Question

The program loops 1-10 but the user can choose whether they want to print only the even numbers, only the odd numbers, or all the numbers.

So, if the user choose to print only evens then the output should be: 2 4 6 8 10

If only odd: 1 3 5 7 9

All: 1 2 3 4 5 6 7 8 9 10

But when I run my code below, it works normally for print all but for print only even or print only odd then it won't run the program at all. So I was wondering what may be the mistakes here.

MODE = ["Only Even", "Only Odds", "All Numbers"]
for i,v in enumerate(MODE):
    print i+1, v
count = 0
s = int(input("Enter Mode Wanted: "))
if s == 3:
    while count < 10:
        print count+1
    count += 1
elif s == 2:
    while count <=10:
        if count%2 != 0:
            print count
    count += 1
elif s == 1:
    while count <= 10:
        if count%2 == 0:
            print count
    count += 1

I've made some more changes to my code. Be sure to check them out. — sshashank124, May 05 '14 at 13:27

score 2 · Accepted Answer · answered May 05 '14 at 13:21

2

Your count += 1 indentation is wrong.

CORRECTED:

MODE = ["Only Even", "Only Odds", "All Numbers"]
for i,v in enumerate(MODE):
    print i+1, v
count = 1                 #changed 0 to 1
s = int(raw_input("Enter Mode Wanted: "))
if s == 3:
    while count <= 10:    #changed < to <=
        print count       #changed count+1 to count
        count += 1
elif s == 2:
    while count <=10:
        if count%2 != 0:
            print count
        count += 1
elif s == 1:
    while count <= 10:
        if count%2 == 0:
            print count
        count += 1

answered May 05 '14 at 13:21

sshashank124

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So my biggest mistake was the indentation of count += 1 ryt? But why didn't the program run when I enter s = 1 or 2 in my code, does it have to do with the indentation? or is there other reason? – avoid_frustration May 05 '14 at 13:34
@avoid_frustration, Please try my code as is. I made very few adjustments to it. It works. I tested it – sshashank124 May 05 '14 at 13:36
Yea, I've tried and it works! I was just wondering what were my mistakes. – avoid_frustration May 05 '14 at 13:37
@avoid_frustration, I'm not sure. I just copied your code and edited some of it. You can see where I put the comments. – sshashank124 May 05 '14 at 13:39
Yea, the comments helps! Thanks for the answer, did help a lot! :) – avoid_frustration May 05 '14 at 13:40

score 0 · Answer 2 · edited May 23 '17 at 12:05

First, rather than use a while loop, you should use a for loop in cases like this, where you know what you are iterating over:

for count in range(1, 11):

thus saving you from the error of forgetting to manually increment count (or incrementing it in the wrong place, in this case).

Second, you should run this loop only once, and move your rules inside it:

for count in range(1, 11):    
    if (s == 3 or 
        (s == 2 and count % 2 != 0) or 
        (s == 1 and count % s == 0)):
        print count

Note how this significantly reduces duplication and, thus, potential for error.

Finally, you can use this question, str.format and the optional second argument to enumerate to improve your user input:

MODE = ["Only Even", "Only Odds", "All Numbers"]
for i, v in enumerate(MODE, 1):
    print "{0}: {1}".format(i, v)
while True:
    try:
        s = int(input("Enter mode wanted: "))
    except ValueError:
        print("Not an integer.")
    else:
        if s in range(1, len(MODE) + 1):
            break
        print("Not a valid mode.") 
for count in range(1, 11):
    ...

Looping 1-10 PRINT either only EVEN, only ODDS, or ALL

2 Answers2