What is the usage of the replace function in Python?

The replace function in Python is used to replace old characters with new characters in a string. Its basic syntax is as follows:

str.replace(old, new, count)

Parameter explanation:

1. old: The old character or substring that needs to be replaced.
2. replacement: the new character or substring after substitution.
3. Count: specifies the number of times to replace. If this parameter is not specified, all replacements will be made.

The replace function will return a new string without modifying the original string.

Here are some examples:

text = "Hello, World!"
new_text = text.replace("o", "e")
print(new_text)  # 输出：Helle, Werld!

text = "Hello, World!"
new_text = text.replace("o", "e", 1)
print(new_text)  # 输出：Helle, World!

In the first example, all “o” are replaced with “e”. In the second example, only the first “o” is replaced with “e” because we specified the replacement count as 1 through the count parameter.

It is important to note that the replace function performs exact match replacements, meaning it will only replace when the old character or substring matches completely. If pattern matching replacements are needed, regular expressions and related functions in the re module can be used.