String Find in Python

In Python, you can find the index of a substring using find():

s.find(sub)         # returns index of first occurrence, or -1 if not found
s.index(sub)        # like find(), but raises ValueError if not found
s.find(sub, start)  # search starting from index `start`

Here are some examples:

sentence = "Hello World"
idx = sentence.find("World")
print(idx)  # 6

print(sentence.find("xyz"))  # -1  (not found)

The index returned is the position of the first character of the found substring.