rindex() : Find the rightmost matching of the search string and return the position in Python

Find the rightmost matching of search string and return the position

main_string.rindex(search_string, start, end)

search_string

Required, String to be searched and position is returned if found.

start

Optional, Starting position of search , by default it is from 0 or starting position of string

end

Optional , ending position of search, by default it is end of the string.

This is case sensitive search

my_str='Welcome to plus2net.com Python section'
output=my_str.rindex('co') 
print(output) # output is 20

Using optional parameters start and end.

my_str='Welcome to plus2net.com Python section'
output=my_str.rindex('co',10,22)
print(output) # output is 20

If search string is not found then value error is generated.

my_str='Welcome to plus2net.com Python section'
output=my_str.rindex('co',10,21)
print(output)

Output

ValueError                        Traceback (most recent call last)
 in ()
      1 my_str='Welcome to plus2net.com Python section'
----> 2 output=my_str.rindex('co',10,21)
      3 print(output)

ValueError: substring not found

rindex() method raise an exception if searched string is not found but rfind() returns -1 if searched string is not found. That is the main difference between rindex() and rfind()

Example: Locating Last Occurrence of a Word

The `rindex()` method can be used to find the last occurrence of a word within a string, which is useful for parsing or analyzing text.

my_str = "Find the last apple in the apple orchard"
position = my_str.rindex("apple")
print("Last 'apple' found at index:", position)

Last 'apple' found at index: 27

Use Case: Extracting Text After the Last Delimiter

If we want to extract text after the last occurrence of a delimiter (e.g., a period or slash), `rindex()` can be extremely helpful.

file_path = "user/documents/reports/summary.pdf"
last_slash = file_path.rindex("/")
file_name = file_path[last_slash + 1:]
print("File name:", file_name)

File name: summary.pdf

Advanced Example: Using `rindex()` with Start and End Parameters

We can specify search limits using the start and end parameters to find occurrences within a defined range.

my_str = "error1: info; error2: critical; error3: debug"
position = my_str.rindex("error", 0, 20)
print("Last 'error' found in range:", position)

Last 'error' found in range: 14

Example: Handling `ValueError` Exception

The `rindex()` method raises a `ValueError` if the substring is not found. We can handle this using a try-except block.

try:
    position = "Hello World".rindex("Python")
    print("Position:", position)
except ValueError:
    print("Substring not found")

Output

Substring not found

All String methods

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Subhendu Mohapatra

Author & Instructor at plus2net

I write and maintain practical tutorials on Python, PHP, SQL, JavaScript, HTML, jQuery, and web development at plus2net. The tutorials focus on clear explanations, working examples, and code that readers can test and adapt while learning.

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