How is the replace function used in Python?

In Python, the replace function is used to substitute substrings within a string.

The basic syntax of the replace function is as follows:

new_string = string.replace(old, new, count)

In this case, the “string” refers to the string in which the replacement operation will be performed, “old” is the substring to be replaced, “new” is the new substring after replacement, and “count” is an optional parameter indicating the maximum number of replacements.

The code example is as follows:

string = "Hello, World!"
new_string = string.replace("Hello", "Hi")
print(new_string)  # 输出: Hi, World!

In the example above, we replaced “Hello” in the string with “Hi”.

If the optional parameter count is not specified, all matched substrings will be replaced by default. If count is specified, it will replace a maximum of count times.

Here is an example code:

string = "Hello, Hello, Hello!"
new_string = string.replace("Hello", "Hi", 2)
print(new_string)  # 输出: Hi, Hi, Hello!

In the example above, we replaced the first two occurrences of “Hello” in the string with “Hi”, while the third “Hello” remained unchanged.

It is important to note that the replace function returns a new string and does not modify the original string. If you want to modify the original string, you can assign the replacement result to the original string variable.

The sample code is as follows:

string = "Hello, World!"
string = string.replace("Hello", "Hi")
print(string)  # 输出: Hi, World!