1.4 String basics
2 min read•june 24, 2024
Strings are fundamental building blocks Python, allowing you to work with text data. They're created using quotes, can be manipulated with various operations, and have properties like length that you can easily determine.
Understanding basics is crucial for text processing in Python. You'll learn how to create, combine, and modify strings, as well as access individual characters and perform comparisons between different strings.
String Fundamentals
String creation with quotes
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- Create strings by enclosing a sequence of characters in single quotes ('') or double quotes ("")
- Ensure the opening and closing quotation marks match to avoid syntax errors
- Include special characters in strings using which start with a backslash ($$ followed by a character ( for newline, for tab, \ for backslash, ' for single quote, " for double quote)
- Examples: 'Hello, world!', "This is a string", 'It's a beautiful day', "She said, "Hello!"", 'Line 1\nLine 2\tTabbed'
Length determination with len()
- Determine the number of characters in a string using the function which returns an integer value
- Include all characters in the length count, such as spaces and special characters
- Examples: len('Hello') returns 5, len('Hello, world!') returns 13, len('') returns 0 for an empty string
String concatenation with +
- Join two or more strings together using the + operator, creating a new string without modifying the original strings
- Overload the + operator for strings, causing it to behave differently than when used with numbers
- Convert non-string values to strings using () before concatenating them with other strings
- Examples: 'Hello' + ', ' + 'world!' results in 'Hello, world!', 'a' + 'b' + 'c' results in 'abc', 'Number: ' + str(42) results in 'Number: 42'
String operations and representations
- Access individual characters in a string using , where the first character is at index 0
- Perform various operations on strings using , such as upper(), lower(), strip(), and split()
- Compare strings using comparison operators (==, !=, <, >, <=, >=) which use lexicographic ordering based on or character representations
- ASCII and Unicode are character encoding standards that assign numeric values to characters, allowing computers to represent and manipulate text
Key Terms to Review (20)
\n: The newline character, denoted as '\n', is a special character in programming that represents the end of a line of text and the start of a new line. It is a fundamental concept in input/output operations, string basics, and string manipulation in Python.
\t: \t is a special character in programming languages, including Python, that represents a horizontal tab. It is used to insert a tab space, which can be useful for aligning text or creating formatted output.
ASCII: ASCII, or the American Standard Code for Information Interchange, is a character encoding standard that assigns numerical values to represent various characters, including letters, numbers, and symbols. This encoding system is fundamental to the way computers and digital devices process and store text-based information.
Concatenation: Concatenation is the operation of joining two or more strings end-to-end to create a single string. This process is a fundamental aspect of working with text in programming, as it allows for dynamic string creation, manipulation, and formatting. Understanding concatenation is essential for tasks involving user input, data display, and creating readable outputs in code.
Escape Sequences: Escape sequences are special characters in programming that are used to represent non-printable characters or to perform specific actions within a string. They are typically preceded by a backslash (\) and are used to add formatting, control, or special characters to a string.
F-strings: F-strings, also known as formatted string literals, are a powerful feature in Python that allow for easy and efficient string formatting. They provide a concise way to embed expressions directly within string literals, making it simpler to create dynamic and customizable strings.
Format specifier: A format specifier is a sequence of characters used in strings to define how values should be formatted. It allows for the integration of variables and their formatting within string literals.
Format(): The format() method in Python is a versatile tool used to format and customize the output of strings. It allows you to insert values into a string, apply various formatting options, and create dynamic and readable text output.
Immutability: Immutability refers to the property of an object or a variable where its value cannot be changed or modified once it has been created. This concept is fundamental in programming and has important implications in various contexts, including string operations, tuple handling, and dictionary management.
In: The term 'in' is a preposition that is used to indicate location, time, or inclusion within a specific context. It is a fundamental part of the English language and plays a crucial role in various programming concepts, including string manipulation, list operations, dictionary usage, and control flow structures.
Indexing: Indexing is the process of accessing specific elements within a data structure, such as a string, list, or array, by their position or index. It allows for the retrieval, manipulation, and identification of individual components within a larger collection of data.
Input: Input in Python is data provided by the user to the program, typically through the keyboard. It can be captured using the input() function and stored in variables for further processing.
Input(): The input() function in Python is used to receive data from the user during the execution of a program. It allows the program to pause and wait for the user to enter some information, which is then stored in a variable for further processing.
Len(): The len() function is a built-in function in Python that returns the length or count of elements in a given object, such as a string, list, tuple, or dictionary. It is a fundamental operation that is widely used across various programming topics in Python.
Slicing: Slicing is a fundamental operation in Python that allows you to extract a subset of elements from a sequence, such as a string, list, or other iterable data structures. It provides a powerful way to access and manipulate data by specifying the start, stop, and step of the desired subset.
Str: The str (string) data type in Python is a collection of one or more characters that can include letters, digits, and various symbols. Strings are used to represent and manipulate textual data within a Python program.
String: A string is a sequence of characters, such as letters, numbers, and symbols, that is used to represent and store textual data in programming. Strings are a fundamental data type in many programming languages, including Python, and are essential for tasks such as text manipulation, data storage, and communication.
String Comparison: String comparison refers to the process of evaluating and comparing the values of two or more strings to determine their relationship, such as whether they are equal, one is greater than the other, or they are lexicographically ordered. This concept is fundamental in programming and is utilized across various topics related to string manipulation and processing.
String Methods: String methods are built-in functions in Python that allow you to perform various operations and manipulations on string data types. These methods provide a wide range of functionalities, from modifying the case of characters to searching, splitting, and joining strings, making it easier to work with and process textual information.
Unicode: Unicode is a universal character encoding standard that provides a unique number for every character, regardless of the platform, program, or language. It aims to enable the consistent representation and handling of text expressed in most of the world's writing systems.