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Python: Change a given string to a new string where the first and last chars have been exchanged

Python String: Exercise-10 with Solution

Write a Python program to change a given string to a new string where the first and last chars have been exchanged.

Python String Exercises: Change a given string to a new string where the first and last chars have been exchanged

Sample Solution:-

Python Code:

def change_sring(str1):
      return str1[-1:] + str1[1:-1] + str1[:1]
	  
print(change_sring('abcd'))
print(change_sring('12345'))

Sample Output:

dbca                                                                                                          
52341

Flowchart:

Flowchart: Change a given string to a new string where the first and last chars have been exchanged

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Python Code Editor:

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Python: Tips of the Day

Check if a given key already exists in a dictionary:

In is the intended way to test for the existence of a key in a dict.

d = {"key1": 10, "key2": 23}

if "key1" in d:
    print("this will execute")

if "nonexistent key" in d:
    print("this will not")

If you wanted a default, you can always use dict.get():

d = dict()

for i in range(100):
    key = i % 10
    d[key] = d.get(key, 0) + 1

and if you wanted to always ensure a default value for any key you can either use dict.setdefault() repeatedly or defaultdict from the collections module, like so:

from collections import defaultdict

d = defaultdict(int)

for i in range(100):
    d[i % 10] += 1

but in general, the in keyword is the best way to do it.

Ref: https://bit.ly/2XPMRyz