Python reverse string

Python-3/basic_examples/strings/string_reverse.py

@@ -0,0 +1,79 @@
+# reverse using while loop, string is a sequence
+def reverse_while_loop(s):
+    s1 = ''
+    length = len(s) - 1
+    while length >= 0:
+        s1 = s1 + s[length]
+        length = length - 1
+    return s1
+
+
+# reverse using for loop
+def reverse_for_loop(s):
+    s1 = ''
+    for c in s:
+        s1 = c + s1  # appending chars in reverse order
+    return s1
+
+
+# reverse using slicing
+def reverse_slicing(s):
+    return s[::-1]
+
+
+# using join with reversed iterator
+def reverse_join_reversed_iter(s):
+    s1 = ''.join(reversed(s))
+    return s1
+
+
+# reverse using recursion
+def reverse_recursion(s):
+    if len(s) == 0:
+        return s
+    else:
+        return reverse_recursion(s[1:]) + s[0]
+
+
+# using list reverse()
+def reverse_list(s):
+    temp_list = list(s)
+    temp_list.reverse()
+    return ''.join(temp_list)
+
+
+input_str = 'ABç∂EF'
+
+if __name__ == "__main__":
+    print('Reverse String using while loop =', reverse_while_loop(input_str))
+    print('Reverse String using for loop =', reverse_for_loop(input_str))
+    print('Reverse String using slicing =', reverse_slicing(input_str))
+    print('Reverse String using reversed() and join() =', reverse_join_reversed_iter(input_str))
+    print('Reverse String using Recursion =', reverse_recursion(input_str))
+    print('Reverse String using list reverse =', reverse_list(input_str))
+
+'''
+Running these functions one by one with timeit module to identify the best one. 
+Slicing is the fastest and smallest way to reverse a string and should be preferred to reverse a string.
+
+$python3.7 -m timeit --number 100000 --unit usec 'import string_reverse' 'string_reverse.reverse_slicing("ABç∂EF"*10)'
+100000 loops, best of 5: 0.449 usec per loop
+
+$python3.7 -m timeit --number 100000 --unit usec 'import string_reverse' 'string_reverse.reverse_list("ABç∂EF"*10)'
+100000 loops, best of 5: 2.46 usec per loop
+
+$python3.7 -m timeit --number 100000 --unit usec 'import string_reverse' 'string_reverse.reverse_join_reversed_iter("ABç∂EF"*10)'
+100000 loops, best of 5: 2.49 usec per loop
+
+$python3.7 -m timeit --number 100000 --unit usec 'import string_reverse' 'string_reverse.reverse_for_loop("ABç∂EF"*10)'
+100000 loops, best of 5: 5.5 usec per loop
+
+
+$ python3.7 -m timeit --number 100000 --unit usec 'import string_reverse' 'string_reverse.reverse_while_loop("ABç∂EF"*10)'
+100000 loops, best of 5: 9.4 usec per loop
+
+
+$python3.7 -m timeit --number 100000 --unit usec 'import string_reverse' 'string_reverse.reverse_recursion("ABç∂EF"*10)'
+100000 loops, best of 5: 24.3 usec per loop
+
+'''