replace() method is used to replace a specified substring with another substring in a string. It returns a new string with the replacements applied, while the original string remains unchanged.

s = "Python is fun. Python is powerful."
res = s.replace("Python", "Coding")
print(res)

Coding is fun. Coding is powerful.

Explanation:

• replace("Python", "Coding") replaces every occurrence of "Python" with "Coding".
• A new string is returned with the updated values, original string s remains unchanged.

Syntax

string.replace(old, new, count)

Parameters:

• old: substring that needs to be replaced.
• new: substring that will replace old.
• count (optional): Specifies the maximum number of replacements to perform. If omitted, all occurrences are replaced.

Return Value: A new string with the specified replacements applied. The original string is not modified because strings in Python are immutable.

Examples

Example 1: Here, only the first occurrence of a substring is replaced using the count parameter.

s = "apple apple apple"
res = s.replace("apple", "orange", 1)
print(res)

orange apple apple

Explanation: s.replace("apple", "orange", 1) replaces "apple" only once due to count=1.

Example 2: This example demonstrates that replace() treats uppercase and lowercase characters as different, replacing only exact matches.

s = "Hello World! hello world!"
res1 = s.replace("Hello", "Hi")
res2 = s.replace("hello", "hi")
print(res1)
print(res2)

Hi World! hello world!
Hello World! hi world!

Explanation:

• s.replace("Hello", "Hi") affects only the capitalized "Hello".
• s.replace("hello", "hi") affects only the lowercase "hello".

Example 3: In this example, replace() is used multiple times to clean and reformat a phone number.

phone = "123-456-7890"
res = phone.replace("-", " ")
print(res)

123 456 7890

Explanation: replace("-", " ") replaces each hyphen (-) with a space.