Python How To Convert This For Loop Into A While Loop

Possible Duplicate: Converting a for loop to a while loop I have this for a for loop which I made I was wondering how I would write so it would work with a while loop. def scrol

Solution 1:

Well, you are nearly there. It's like this:

defscrollList2(myList):
    negativeIndices=[]
    i= 0
    length= len(myList)
    while i != length:
        if myList[i]<0:
            negativeIndices.append(i)
        i=i+1return negativeIndices

The problem you had is that you must increment the loop index on each iteration. You were only incrementing when you found a negative value.

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But it's better as a for loop and your for loop is over complicated. I'd write it like this:

defscrollList(myList):
    negativeIndices=[]
    for index, item inenumerate(myList):
        if item<0:
            negativeIndices.append(index)
    return negativeIndices

Solution 2:

Well, for one, your incrementer i should always be updated, instead of just when you meet the condition. Only doing it in the if statement means you're only ever advancing when you see a returnable element, so if your first element doesn't meet your condition, your function will hang. Oops. This would work better:

defscrollList2(myList):
    negativeIndices=[]
    i= 0
    length= len(myList)
    while i != length:
        if myList[i]<0:
            negativeIndices.append(i)
        i=i+1return negativeIndices