Python String find() Method

Python find substring index in string; In this tutorial, i am going to show you how to find substring index in string in python.

To find the index or position of the first occurrence of a substring from the given string in python; so in this tutorial, i will show you two methods which is used to find the index or position of the first occurrence of a substring from the given string in python .

How to Find String Index or Position in Python

Use the following python find() and rfind() methods to find index or position of substring from string in python:

  • Python String Find()
  • Python String rfind()

Python String Find()

The python find() method finds the lowest substring of the given string. If the substring found in a given string, it returns index of the substring. Otherwise, it returns -1.

The syntax of find() method is:

str.find(sub[, start[, end]] )

Parameters of find() method

The find() method takes a maximum of three parameters:

  • sub – It’s the substring to be searched in the str string.
  • start and end (optional) – substring is searched within str[start:end]

Return Value from python find()

The find() method returns an integer value.

  • If substring exists inside the string, it returns the index of first occurence of the substring.
  • If substring doesn’t exist inside the string, it returns -1.

Example 1: Python find() method with No start and end Argument

string = 'Hello python learners, welcome to python course'
result = string.find('python')
print("Substring 'python':", result)

Output

Substring 'python': 6

Example 2: python find() method with start and end arguments

string = 'Hello python learners, welcome to python course'
# Substring is searched
print(string.find('welcome ', 6, 50))

Output

23

Python String rfind()

The python rfind() method finds the highest substring of the given string. If the substring found in a given string, it returns the index of the substring. Otherwise, it returns -1.

The syntax of rfind() is:

str.rfind(sub[, start[, end]] )

Parameters of rfind() method

The rfind() method takes maximum of three parameters:

  • sub – It’s the substring to be searched in the str string.
  • start and end (optional) – substring is searched within str[start:end]

Return Value from rfind() method

The rfind() method returns an integer value.

  • If substring exists inside the string, it returns the highest index where substring is found.
  • If substring doesn’t exist inside the string, it returns -1.

Example 1: Python rfind() method with No start and end Argument

string = 'Hello python learners, welcome to python course'
result = string.rfind('python')
print("Substring 'python':", result)

Output

Substring 'python': 34

Example 2: python find() method with start and end arguments

string = 'Hello python learners, welcome to python course'
# Substring is searched
print(string.find('to', 6, 50))

Output

31

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