How to understand str in python, and how to use str function in python

Understanding the str type and str() function usage in Python is one of the bases for understanding Python programming language. This article will deeply discuss the definition, characteristics, common operations of str type and the usage of str() function to help beginners better understand and use these key concepts.

What is the str type?

In Python, str is a data type, representing string. A string is a sequence of characters, which can be letters, numbers, symbols, or other printable characters. Strings in Python are immutable, which means that once created, their contents cannot be changed. Strings are very important in Python because they are used to store and process text data.

Create String

To create a string, you can use single quotation marks or double quotation marks to enclose the text as follows:

Both methods can be used to create strings and include quotation marks in the strings, for example:

Basic operation of string

String concatenation

Use the plus sign (+) to connect two strings:

Duplicate string

You can use the multiplication sign (*) to repeat a string multiple times:

Get string length

To get the length of a string, you can use the len() function:

Common methods of string

Python provides many useful string methods for performing various operations. Here are some common methods:

The strip() method is used to remove white space characters (spaces, tabs, newlines, etc.) at the beginning and end of a string:

The split() method is used to split a string into substrings and return a list:

The join() method is used to combine a list of strings into a single string:

The replace() method is used to replace a substring in a string:

These two methods are used to find the position of the substring in the string. The find () method returns the index of the first occurrence of the substring, or - 1 if it is not found. The index() method also returns the first index of the substring, but if it is not found, an exception will be thrown.

toggle case

The upper() method is used to convert the string to uppercase, and the lower() method is used to convert the string to lowercase:

format string

In Python, you can format strings in many ways, including using the% operator, the str. format() method, and f-strings (formatting string literals). The following are examples of these methods:

Use the% operator

Use f-strings

Usage of str() function

In addition to string literals, you can also use the str() function to convert other data types to strings. This is useful when connecting numbers or other non string data to strings.

In Python, the str type is a very important data type for processing text data. We have discussed how to create, manipulate, and format strings, and how to use the str () function to convert other data types to strings. These basic knowledge are very important for writing Python programs and processing text data. I hope this article can help you better understand and utilize the application of strings in Python. If you want to learn more, you can also study more advanced operations and methods related to strings.