[FIXED] how to find the length of a list in python without using len()

Issue

I want to write a function which will find out the length of a list based on user input. I don't want to use the in-built function len(). PLease help me. Function which i have written is working for strings but for lists it is failing.

#function for finding out the length
def string_length(a):
    for i in a:
        j+=1
    return j

#taking user input
a = input("enter string :")
length = string_length(a)
print("length is ", length)

Solution

You probably need to initialize your variable j (here under renamed counter):

def string_length(my_string):
    """returns the length of a string
    """
    counter = 0
    for char in my_string:
        counter += 1
    return counter

# taking user input
string_input = input("enter string :")
length = string_length(string_input)

print("length is ", length)

This could also be done in one "pythonic" line using a generator expression, as zondo has pointed out:

def string_length(my_string):
    """returns the length of a string
    """
    return sum(1 for _ in my_string)

Answered By - Reblochon Masque