Check if a Substring Exists in a String in Python

April 27, 2024

Here are 2 ways to check if a substring exists in a string in Python:

(1) Using the “in” keyword:

my_string = "This is an example of a string"
my_substring = "example"

if my_substring in my_string:
    print("Substring found")
else:
    print("Substring not found")

The result:

Substring found

(2) Using the “find()” method:

my_string = "This is an example of a string"
my_substring = "example"

if my_string.find(my_substring) != -1:
    print("Substring found")
else:
    print("Substring not found")

The result:

Substring found

Note that the “!= -1” means that if the result of the “find()” method is different from -1, the substring is actually found. Else, when the “find()” method returns -1, the substring is not found.

Examples of Substrings Not Found

(1) Using the “in” keyword:

my_string = "This is an example of a string"
my_substring = "hello"

if my_substring in my_string:
    print("Substring found")
else:
    print("Substring not found")

The result:

Substring not found

(2) Using the “find()” method:

my_string = "This is an example of a string"
my_substring = "hello"

if my_string.find(my_substring) != -1:
    print("Substring found")
else:
    print("Substring not found")

The result:

Substring not found

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