Python String find() Method

The find() method in Python helps you locate the position of a substring inside another string. It's a safe way to check if a word or character exists and find where it appears first.

Syntax

string.find(substring, start, end)

Parameters:

• substring – The string you want to find inside the main string (required).
• start – The position to start the search (optional).
• end – The position to end the search (optional).

Returns:

• Index (integer) of the first occurrence of the substring.
• Returns -1 if the substring is not found.

Example 1: Basic Usage

text = "Python programming is fun"
position = text.find("programming")
print(position)

7

Why? Because the word "programming" starts at index 7 in the string.

Example 2: Substring Not Found

print("apple".find("z"))

-1

Note: find() doesn't crash if the substring isn't found – it simply returns -1.

Example 3: Using Start and End

text = "learn learn learn"
position = text.find("learn", 6)
print(position)

6

Here, we told Python to start looking from index 6. It finds the second "learn" starting at index 6.

Real-Life Use Case

Use find() to check if a user input contains certain keywords:

message = "Please confirm your email address"
if message.find("confirm") != -1:
    print("Confirmation keyword found!")

Confirmation keyword found!

Difference Between find() and index()

• find() returns -1 if not found
• index() raises a ValueError if not found

Common Mistakes

• Forgetting that find() is case-sensitive ("Hello".find("h") returns -1)
• Using == 0 instead of != -1 when checking if something exists

Summary

• find() helps locate substrings inside strings
• Returns index if found, or -1 if not
• Safe to use even if the substring doesn't exist

Practice Problem

Ask the user to enter a sentence and search for the word "Python". Print the result.

sentence = input("Enter a sentence: ")
index = sentence.find("Python")
if index != -1:
    print("Found 'Python' at index", index)
else:
    print("'Python' not found")