A substring is a sequence of characters within a String. When writing a Python program you may need to check whether a substring is present inside another string or not, there can be many reasons for that like searching and filtering data, input validation, etc.<\/p>\n\n\n\n
To check if a string contains a substring, we can utilise many built-in functions that Python provides us, each one with slightly different functionality. <\/p>\n\n\n\n
At the end of this tutorial, you will not only know how to check for substrings but also know a lot of new Python methods, so let’s get started.<\/p>\n\n\n\n
Python has various methods for this check, but we’ll be using those that are easy to implement and require only a few lines of code.<\/p>\n\n\n\n
The following are the methods in Python to check if a string contains other substrings.<\/strong><\/p>\n\n\n\n Now, let’s examine each of them separately, along with their respective syntax and examples.<\/p>\n\n\n\n The find() method is used to check whether a string contains a particular substring or not. It takes a substring as an argument and if the string contains that particular substring, it returns the starting index of the substring else it returns -1.<\/p>\n\n\n\n Syntax<\/strong>:<\/p>\n\n\n Here, substring<\/strong> is the string you want to search, and string <\/strong>is the string object in which you want to search.<\/p>\n\n\n\n Example:<\/strong><\/p>\n\n\n Output<\/strong>:<\/p>\n\n\n The ‘in’ operator checks for the presence of a substring within a string by returning either True or False. If the substring is present it returns True<\/strong> else it returns False<\/strong>.<\/p>\n\n\n\n Syntax<\/strong>:<\/p>\n\n\n Example:<\/strong><\/p>\n\n\n Output<\/strong>:<\/p>\n\n\n The count() method checks for the occurrence of a substring in a string. If the substring is not found in the string, it returns 0.<\/p>\n\n\n\n Syntax<\/strong>:<\/p>\n\n\n Example:<\/strong><\/p>\n\n\n Output<\/strong>:<\/p>\n\n\n This method can also check for a substring’s presence in a\u00a0string. If the substring is not present in the string then it doesn’t return any value, rather it generates a ValueError<\/strong>.<\/p>\n\n\n\n Syntax<\/strong>:<\/p>\n\n\n Example:<\/strong><\/p>\n\n\n Output<\/strong>:<\/p>\n\n\n We can also use the operator.contains() method of the “operator” module to check for substrings. It takes a string and a substring as an argument and returns a boolean True if the substring is contained in that string, else it returns False.<\/p>\n\n\n\n Syntax<\/strong>:<\/p>\n\n\n Example:<\/strong><\/p>\n\n\n Output<\/strong>: <\/p>\n\n\n In this tutorial, we explored five ways to check if a string contains a substring. Each method offers its own advantages and suitability for different scenarios. Among them, the best way to check whether a Python string contains another string is to use With this knowledge, you can efficiently check if string contains a substring in Python programming language. Additionally, there is another method, string.__contains__(), which provides a more efficient way of performing this check. For a detailed tutorial specifically covering this method, you can read “Python String Contains: Check if a String Contains a Substring<\/a>“. Hope you have enjoyed reading the content.<\/p>\n\n\n\n\n
Using the find() Method<\/h2>\n\n\n\n
\nstring.find(substring)\n<\/pre><\/div>\n\n\n
\nstr="Safa Mulani is a student of Engineering discipline." \nsub1="Safa" \nsub2="Engineering" \n\nprint(str.find(substring1)) \n\nprint(str.find(substring2))\n<\/pre><\/div>\n\n\n
\n0\n28\n<\/pre><\/div>\n\n\n
Using the ‘in’ operator<\/h2>\n\n\n\n
\nsubstring in string\n<\/pre><\/div>\n\n\n
\nstr="Safa Mulani is a student of Engineering discipline." \nsub1="Safa" \nsub2="Done" \n\nprint(sub1 in str) \n\nprint(sub2 in str)\n<\/pre><\/div>\n\n\n
\nTrue\nFalse\n<\/pre><\/div>\n\n\n
Using the count() Method<\/h2>\n\n\n\n
\nstring.count(substring)\n<\/pre><\/div>\n\n\n
\nstr="Safa Mulani is a student of Engineering discipline." \nsub1="Safa" \nsub2="student" \nsub3="Done"\nprint(str.count(sub1)) \n\nprint(str.count(sub2))\n\nprint(str.count(sub3))\n<\/pre><\/div>\n\n\n
\n1\n1\n0\n<\/pre><\/div>\n\n\n
Using the index() Method<\/h2>\n\n\n\n
\nstring.index(substring)\n<\/pre><\/div>\n\n\n
\nstr = "Safa is a Student."\ntry : \n result = str.index("Safa") \n print ("Safa is present in the string.") \nexcept : \n print ("Safa is not present in the string.") \n<\/pre><\/div>\n\n\n\nSafa is present in the string.\n<\/pre><\/div>\n\n\n
Using the operator.contains() Method<\/h2>\n\n\n\n
\noperator.contains(string, substring)\n<\/pre><\/div>\n\n\n
\nimport operator \n \nstr = "Safa is a Student."\n \nif operator.contains(str, "Student"): \n print ("Student is present in the string.") \nelse : \n print ("Student is not present in the string.") \n<\/pre><\/div>\n\n\n\nStudent is present in the string. \n<\/pre><\/div>\n\n\n
Conclusion<\/h2>\n\n\n\n
for loop<\/code>, as it is easily understandable by beginners, more readable and does not require any additional methods. <\/p>\n\n\n\nReference<\/h2>\n\n\n\n