CODEWITHSUNDEEP
python
Celias
Celias

Reputation: 29

Why is my Python list iteration not working correctly?

I'm trying to make a script where someone can type a username and the script will check if the directory exists, returning true or false as it goes through the list. Currently, the output is always "Not found"/false even though there should definitely be at least one true returned.

def scan():
    username = input("Type in the username here: ") 
    i = 0
    searchFor = folderList[i] + username
    listLength = len(folderList)
    while i < listLength:
        if os.path.isdir(searchFor) == True:
            print ("Folder found!")
            i += 1
        elif os.path.isdir(searchFor) == False:
            print ("Not found")
            i += 1

For reference, this code below which doesn't use a loop works fine, as if I type in the username and the correct index for the element of the directory that exists, it returns true, otherwise if I choose another index it's false as it should, so it's not an issue with the elements or folder permissions.

def test():
    username = input("Type in the username here: ") 
    i = int(input("Type list index number here: "))
    searchFor = folderList[i] + username

    if os.path.isdir(searchFor) == True:
        print("Folder found: " + searchFor)
    else:
        print("Not found!")

Would appreciate any help!

Upvotes: 0

Views: 224

Answers (3)

Hritu Rathod
Hritu Rathod

Reputation: 99

def scan():
username = input("Type in the username here: ") 
i = 0
listLength = len(folderList)
while i < listLength:
    searchFor = folderList[i] + username
    if os.path.isdir(searchFor) == True:
        print ("Folder found!")
        i += 1
    elif os.path.isdir(searchFor) == False:
        print ("Not found")
        i += 1

Upvotes: 1

Carcigenicate
Carcigenicate

Reputation: 45750

I'm writing an answer because the existing answers fail to address the problem, and I think they confuse things more than anything.

You currently have searchFor outside of the loop. As a result, it will be given a value once before the loop is entered, then its value is never changed. If you want its value to change, you must manually reassign it:

while i < listLength:
    searchFor = folderList[i] + username

Although, really, a for loop should be used here instead (but not as @Sai suggests):

for folder in folderList:
    searchFor = folder + username

You never use i for anything other than indexing folderList, so you should just iterate the folderList directly instead. Iterating a range is generally regarded as a code smell if you're just using the number to index a list.

Upvotes: 2

Sai Kumar
Sai Kumar

Reputation: 285

This code will help you 

def scan():
    username = input("Type in the username here: ")
    is_exists = False
    for i in range(0,len(folderList)):
        searchFor = folderList[i] + username
        if os.path.isdir(searchFor):
            is_exists = True
            break

    if is_exists:
        print("Search is found")
    else:
        print("Not Found")

Upvotes: 1

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