Find existing element
Input
find_index_or_minus_one([1, 2, 3], 2)
Output
1
2 is at index 1 in the list.
Full lesson preview
Find element index or return -1
Find the first index of a target in a list, or return -1 if it isn't present.
Python practice10 minLists & TuplesBeginnerLast updated March 17, 2026
Problem statement
Write a function find_index_or_minus_one(lst, target) that searches lst for target and returns the index of the first occurrence. If target is not present, return -1. Do not raise exceptions for missing elements.
Task
Implement a function that returns the index of the first occurrence of target in a list, or -1 when the target is not found.
Examples
Input format
A function call: find_index_or_minus_one(lst, target)
Output format
Return an integer index (or -1 if not found).
Constraints
Use linear search (O(n)). The list may contain mixed types; equality comparison should be used.
Samples
Sample 1
Input
find_index_or_minus_one([], 'x')
Output
-1
Empty list can't contain 'x', so return -1.