Python: Find the index of a given string at which a given substring starts
Python String: Exercise-81 with Solution
Write a Python program to find the index of a given string at which a given substring starts. If the substring is not found in the given string return 'Not found'.
Sample Solution:-
Python Code:
def find_Index(str1, pos):
if len(pos) > len(str1):
return 'Not found'
for i in range(len(str1)):
for j in range(len(pos)):
if str1[i + j] == pos[j] and j == len(pos) - 1:
return i
elif str1[i + j] != pos[j]:
break
return 'Not found'
print(find_Index("Python Exercises", "Ex"))
print(find_Index("Python Exercises", "yt"))
print(find_Index("Python Exercises", "PY"))
Sample Output:
7 1 Not found
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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
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