The Python index method functions similarly to the find method, with the distinction that it raises an error when a match is not found. This method provides the index of the first occurrence of a specified substring, and it will trigger an error if no match exists.
Signature
Example
index(sub[, start[, end]])
Parameters
- sub : substring
- start : start index a range
- end : last index of the range
Return Type
If the substring is located, it returns the index of that substring; if not, it raises a ValueError.
Let us explore a few examples to gain a better understanding of the index method.
Python String index Method Example 1
Example
# Python index() function example
# Variable declaration
str = "Welcome to our tutorial."
# Calling function
str2 = str.index("at")
# Displaying result
print(str2)
Output:
Python String index Method Example 2
An error is thrown if the substring is not found.
Example
# Python index() function example
# Variable declaration
str = "Welcome to our tutorial."
# Calling function
str2 = str.index("ate")
# Displaying result
print(str2)
Output:
Output
ValueError: substring not found
Python String index Method Example 3
Additionally, we can provide start and end indices as arguments to allow for a more tailored processing experience.
Example
# Python index() function example
# Variable declaration
str = "Welcome to our tutorial."
# Calling function
str2 = str.index("p",19,21)
# Displaying result
print("p is present at :",str2,"index")
Output:
Output
p is present at : 20 index
