How to use the Python replace() String Method
In this tutorial, you'll learn how to use the replace() string method in Python. The replace() method returns a copy of the string with all occurrences of old substring replaced by a new substring.
Python replace() Syntax
The following illustrates the syntax of the replace() string method:
string.replace(old_substring, new_substring [, count])
Method Parameters
- old_substring: Required. The old substring you want to replace.
- new_substring: Required. The new substring which will replace the old substring.
- count: Optional. The replace() method replaces all occurrences of old_substring if omitted.
Examples
Example 1: Replace all Occurrences
The following code replaces all occurrences of Python Programming with Ruby Programming:
description = "Python Programming, C Programming, Python Programming, C++ Programming, C# Programming, Python Programming, Pascal Programming, Python Programming";
str = description.replace("Python Programming", "Ruby Programming")
print(str)
Output:
Ruby Programming, C Programming, Ruby Programming, C++ Programming, C# Programming, Ruby Programming, Pascal Programming, Ruby Programming
Example 2: Replace Only a Specified Number of Occurrences
The following example illustrates an example of how to replace only the first two occurrences of Python Programming with Ruby Programming:
description = "C Programming, Python Programming, C++ Programming, Python Programming, C# Programming, Python Programming, Pascal Programming, Python Programming";
str = description.replace("Python Programming", "Ruby Programming")
print(str)
Output:
C Programming, Ruby Programming, C++ Programming, Ruby Programming, C# Programming, Python Programming, Pascal Programming, Python Programming
Example 3: Replace all Occurrences Starting at a Specified Position
You cannot use the replace() method to replace occurrences of an old substring with a new substring, starting at a specified position in the string. However, you can achieve this by writing your program.
Let's say you want to replace the old substring starting at index 60 of a given string.
First, what you need to do is to split the string into two substrings (str1and str2). The str1is the substring, starting at 0 to 60, and str2is the substring, starting at 60 to the end of the string.
Second, replace the old substring with a new substring in str2, and then assign returned substring to a variable named str3.
Third, join str1and str3, and now you'll get the result.
Here is an example:
description = "C Programming, Python Programming, C++ Programming, Python Programming, C# Programming, Python Programming, Pascal Programming, Python Programming";
len = len(description) #get the length of the string
str1 = description[0:60] #get the substring from index 0 to 60
str2 = description[60:len] #get the subtring from index 60 to the end of the string
str3 = str2.replace("Python Programming", "Ruby Programming") #replace Python Programming with Ruby Programming
str = str1 + str3
print (str)
Output:
C Programming, Python Programming, C++ Programming, Python Programming, C# Programming, Ruby Programming, Pascal Programming, Ruby Programming
Example 4: Replace from the End of a String
Replace a substring from the end of a string (replaces only two occurrences of Python with JavaScript):
string = "Python, Java, Python, Java, C++, C#, Visual Basic, Ruby, Python, Python, C#"
reversed_string = string[::-1]
old_substring = "Python"
new_substring = "JavaScript"
reversed_old_substring = old_substring[::-1]
reversed_new_substring = new_substring[::-1]
str = reversed_string.replace(reversed_old_substring, reversed_new_substring, 2)
print (str[::-1])
Output:
Python, Java, Python, Java, C++, C#, Visual Basic, Ruby, JavaScript, JavaScript, C#
In this tutorial, you've learned how to use the Python replace() string method to replace all occurrences of an old substring within a given string with a new substring.