forrevstring.py

# reverse a given string
s=input('enter a string: ')  # s = 'hai'
rev=''
for ele in range(-1,-(len(s)+1),-1):
    rev+=s[ele]
print(rev)

'''Step 1: Initialization
s = "hai" (original string)
rev = "" (empty string to store the reversed result)

Step 2: Set up the for loop
for ele in range(-1, -(len(s)+1), -1):
len(s) = 3 for "hai"
The range becomes range(-1, -4, -1), which means ele will iterate over [-1, -2, -3]

Step 3: Loop Iteration 1 (ele = -1)
s[ele] is s[-1] which is the last character of s, 'i'
rev = rev + s[ele] => "" + "i" = "i"

Step 4: Loop Iteration 2 (ele = -2)
s[ele] is s[-2] which is the second last character of s, 'a'
rev = rev + s[ele] => "i" + "a" = "ia"

Step 5: Loop Iteration 3 (ele = -3)
s[ele] is s[-3] which is the first character of s, 'h'
rev = rev + s[ele] => "ia" + "h" = "iah"

Step 6: End of loop
The loop completes after processing all indices -1, -2, -3
The reversed string stored in rev is "iah"

Step 7: Print the result
print(rev) outputs: iah'''