Have you ever tried to print a mix of text and variable values and ended up with messy code? Python’s f-strings, also known as formatted string literals, are a modern and powerful way to embed expressions inside strings, making your output clean and readable.
✨ What Are F-Strings and How Do They Work?
An f-string is created by prefixing a string with the letter f. Inside this string, you can place variables or any Python expression directly inside curly braces {}, and Python will automatically replace them with their current values. For example: name = "Alice"; print(f"Hello, {name}!") will display “Hello, Alice!”. This is much cleaner than using string concatenation.
💰 Formatting Numbers with F-Strings
F-strings truly shine when you need to format numbers. You can control things like the number of decimal places for a floating-point number. To do this, you add a colon : followed by a format specifier inside the braces. For example, to round a number to two decimal places, you would use :.2f. So, if price = 19.999, print(f"The price is ${price:.2f}") would output “The price is $20.00”.
📊 Aligning Text and Creating Tables
Another powerful feature is controlling the alignment and width of your output, which is perfect for creating tables. You can specify a minimum width for a value and align it to the left (<), right (>), or center (^). For instance, f"{name:>10s}" would right-align the `name` variable within a 10-character space. You can even add comma separators for large numbers automatically with :,d for integers or :,.2f for floats.
F-strings are the go-to method for string formatting in modern Python. They are fast, readable, and incredibly versatile, helping you create professional-looking output with minimal effort.
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Stephenson, Ben. The Python Workbook: A Brief Introduction with Exercises and Solutions. 3rd ed., Springer, 2025.
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