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Python: Find the first repeated character in a given string

Python String: Exercise-53 with Solution

Write a Python program to find the first repeated character in a given string.

Sample Solution:-

Python Code:

def first_repeated_char(str1):
  for index,c in enumerate(str1):
    if str1[:index+1].count(c) > 1:
      return c 
  return "None"

print(first_repeated_char("abcdabcd"))
print(first_repeated_char("abcd"))

Sample Output:

a
None  

Pictorial Presentation:

Python String: Find the first repeated character in a given string
Python String: Find the first repeated character in a given string

Flowchart:

Flowchart: Find the first repeated character in a given string

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Previous: Write a Python program to print all permutations with given repetition number of characters of a given string.
Next:Write a Python program to find the first repeated character of a given string where the index of first occurrence is smallest.

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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