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Python Exercise: Reverse a string

Python Functions: Exercise-4 with Solution

Write a Python program to reverse a string.

Sample String: "1234abcd"
Expected Output: "dcba4321"

Sample Solution-1:

Python Code:

def string_reverse(str1):

    rstr1 = ''
    index = len(str1)
    while index > 0:
        rstr1 += str1[ index - 1 ]
        index = index - 1
    return rstr1
print(string_reverse('1234abcd'))

Sample Output:

dcba4321  

Pictorial presentation:

Python exercises: Reverse a string.

Flowchart:

Flowchart: Python exercises: Reverse a string.

Visualize Python code execution:

The following tool visualize what the computer is doing step-by-step as it executes the said program:


Sample Solution-2:

Python Code:

def reverse(itr):
  return itr[::-1]

str1 = '1234abcd'
print("Original string:",str1)
print("Reverse strig:",reverse('1234abcd'))
str1 = 'reverse'
print("\nOriginal string:",str1)
print("Reverse strig:",reverse(str1))

Sample Output:

Original string: 1234abcd
Reverse strig: dcba4321

Original string: reverse
Reverse strig: esrever

Flowchart:

Flowchart: Python exercises: Reverse a string.

Visualize Python code execution:

The following tool visualize what the computer is doing step-by-step as it executes the said program:


Python Code Editor:

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Previous: Write a Python function to multiply all the numbers in a list.
Next: Write a Python function to calculate the factorial of a number (a non-negative integer). The function accepts the number as an argument.

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Python: Tips of the Day

Find current directory and file's directory:

To get the full path to the directory a Python file is contained in, write this in that file:

import os 
dir_path = os.path.dirname(os.path.realpath(__file__))

(Note that the incantation above won't work if you've already used os.chdir() to change your current working directory, since the value of the __file__ constant is relative to the current working directory and is not changed by an os.chdir() call.)

To get the current working directory use

import os
cwd = os.getcwd()

Documentation references for the modules, constants and functions used above:

  • The os and os.path modules.
  • The __file__ constant
  • os.path.realpath(path) (returns "the canonical path of the specified filename, eliminating any symbolic links encountered in the path")
  • os.path.dirname(path) (returns "the directory name of pathname path")
  • os.getcwd() (returns "a string representing the current working directory")
  • os.chdir(path) ("change the current working directory to path")

Ref: https://bit.ly/3fy0R6m