Index of a variable in a number list in Python

Question

I want to find the index of a variable in a number list.

My code is this:

    arr = [1,2,3,4,5,6,7,8,9]
    x = 8
    a=x
    while x == a:
        b = len(arr)//2
        if arr[b]==x:
    # find the index of x variable

The index() method searches an element in the list and returns its position/index of fist occurrence. — Samsul Islam
– Samsul Islam, Commented Nov 15, 2020 at 16:53

Richa Bhuwania · Accepted Answer · 2020-11-15 17:01:38Z

1

The same problem achieved by the linear search algorithm:

arr = [1,2,3,4,5,6,7,8,9]
x=8
flag = False
index = None
for i in range(len(arr)):
    if arr[i] == x:
        flag = True
        index = i


if not flag:
    print("Number is not present in list.")
else:
    print(index)

answered Nov 15, 2020 at 17:01

Richa Bhuwania

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Comments

Richa Bhuwania · Accepted Answer · 2020-11-15 16:47:09Z

0

If you want to find the index of a variable in a number list, you can directly use the built-in method of python that is index. It gives ValueError if the number is not present in the list.

try:
    arr = [1,2,3,4,5,6,7,8,9]
    x=8
    print(arr.index(x))
except ValueError:
    print("Number is not present in list.")

answered Nov 15, 2020 at 16:47

Richa Bhuwania

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1 Comment

Richa Bhuwania Over a year ago

Then, you can use any of the searching algorithms.

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