How to use f-strings in Python | note.nkmk.me (2024)

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How to use f-strings in Python | note.nkmk.me? ›

To create an f-string, prefix the string with the letter “ f ”. The string itself can be formatted in much the same way that you would with str. format(). F-strings provide a concise and convenient way to embed Python expressions inside string literals for formatting.

To use formatted string literals, begin a string with f or F before the opening quotation mark or triple quotation mark. Inside this string, you can write a Python expression between { and } characters that can refer to variables or literal values.

Using f-strings, your code will not only be cleaner but also faster to write. With f-strings you are not only able to format strings but also print identifiers along with a value (a feature that was introduced in Python 3.8).

Also called formatted string literals, f-strings are string literals that have an f before the opening quotation mark. They can include Python expressions enclosed in curly braces. Python will replace those expressions with their resulting values. So, this behavior turns f-strings into a string interpolation tool.

Python has several tools for string interpolation that support many formatting features. In modern Python, you'll use f-strings or the .format() method most of the time. However, you'll see the modulo operator ( % ) being used in legacy code.

The data to be written is stored in a list called data. The for statement is used to loop over each line of data in the list. The f.write(line + '\n') statement writes each line of data to the file with a newline character (\n) at the end. Finally, the file is automatically closed when the with block ends.

When using quotation marks inside an f-string, you can use either single quotes ('') or double quotes (“”). This allows you to include quotes within your strings without causing syntax errors.

F-strings are faster than str. format() because f-strings are evaluated at compile-time rather than at runtime. When you use an f-string, the expression inside the curly braces is evaluated at compile-time, and the resulting value is inserted into the string.

Using f-strings to format a logging message requires that Python eagerly format the string, even if the logging statement is never executed (e.g., if the log level is above the level of the logging statement), whereas using the extra keyword argument defers formatting until required.

Formatting Numbers With F-Strings

F-strings can also be used to format numbers in various ways, including rounding, padding, and adding prefixes or suffixes. To format a number using F-strings, simply include the number inside the curly braces, followed by a colon and a format specifier.

How do you put an F-string on a new line in Python? ›

The \n characters tell Python to insert newline characters in the final string. Using parentheses, you can create multiline strings with f-strings without having to use triple quotes or escape characters. This can make your code more readable and concise.

The f-string was introduced in Python to make string formatting and interpolation easier. But you can also use it to append strings. To use the f-string, you simply write an f followed by quotation marks: f"" . You can then insert strings and variable names between the quotation marks.

Introduction. The release of Python version 3.6 introduced formatted string literals, simply called “f-strings.” They are called f-strings because you need to prefix a string with the letter 'f' to create an f- string. The letter 'f' also indicates that these strings are used for formatting.

Python f-strings or formatted strings are the new way to format strings. This feature was introduced in Python 3.6 under PEP-498.

A string prefixed with 'f' or 'F' and writing expressions as {expression} is a way to format string, which can include the value of Python expressions inside it. f-string in python lets you format data for printing using string templates.

String Concatenation using f-string

If you are using Python 3.6+, you can use f-string for string concatenation too. It's a new way to format strings and introduced in PEP 498 - Literal String Interpolation. Python f-string is cleaner and easier to write when compared to format() function.

In Python, the . 2f format specifier is used to format floating-point numbers as strings with two decimal places. This format specifier is part of the Python strings format syntax in Python.

F Strings are just a shorthand for str. format - and while they are convinient, they can't do a lot of things that str. format can. For example, with str. format , you can fetch the format string from somewhere (maybe user input / config) and then format your input using that format string.

Another way to create a string with an apostrophe is to use the escape character backslash \ before the apostrophe itself. # Create a string with an apostrophe using the backslash \. I enjoyed last night's concert.