How to resolve the algorithm Variable declaration reset step by step in the Python programming language

Published on 12 May 2024 09:40 PM
#Python

How to resolve the algorithm Variable declaration reset step by step in the Python programming language

Table of Contents

Problem Statement

A decidely non-challenging task to highlight a potential difference between programming languages. Using a straightforward longhand loop as in the JavaScript and Phix examples below, show the locations of elements which are identical to the immediately preceding element in {1,2,2,3,4,4,5}. The (non-blank) results may be 2,5 for zero-based or 3,6 if one-based. The purpose is to determine whether variable declaration (in block scope) resets the contents on every iteration. There is no particular judgement of right or wrong here, just a plain-speaking statement of subtle differences. Should your first attempt bomb with "unassigned variable" exceptions, feel free to code it as (say) If your programming language does not support block scope (eg assembly) it should be omitted from this task.

Let's start with the solution:

Step by Step solution about How to resolve the algorithm Variable declaration reset step by step in the Python programming language

The provided Python code processes a list s containing integers and identifies the indices where consecutive elements are equal. It does so by iterating through the list and comparing each element to the previous one.

  1. s = [1, 2, 2, 3, 4, 4, 5]: This initializes a list s with the given values.

  2. for i in range(len(s)): This loop iterates through each index i in the list s, from 0 to len(s) - 1.

  3. curr = s[i]: For each index i, it assigns the current element at that index to the variable curr.

  4. if i > 0 and curr == prev: Within the loop, it checks two conditions:

    • i > 0: This condition ensures that it only considers indices greater than 0 because there is no previous element to compare for index 0.
    • curr == prev: This condition checks if the current element curr is equal to the previously stored element prev.

  5. print(i): If both conditions are met, meaning that the current element is equal to the previous one and i is not 0, it prints the current index i to the console.

  6. prev = curr: After processing the current element, it updates the prev variable to the current element curr for comparison in the next iteration.

In the provided example list s, there are three instances where consecutive elements are equal: 2, 4, and 4. Therefore, the code will print the following indices:

1
4
5

Source code in the python programming language

s = [1, 2, 2, 3, 4, 4, 5]
 
for i in range(len(s)):
    curr = s[i]
    if i > 0 and curr == prev:
        print(i)
    prev = curr

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