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articles/snippets/6-python-f-strings-tips.md

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+---
+title: 6 Python f-strings tips and tricks
+type: story
+tags: [python,string]
+author: chalarangelo
+cover: sea-view
+excerpt: Python's f-strings can do a lot more than you might expect. Learn a few useful tips and tricks in this quick guide.
+dateModified: 2021-07-20T05:00:00-04:00
+---
+
+Python's f-strings provide a more readable, concise and less error-prone way to format strings than traditional string formatting. They are packed with useful features that are sure to come in handy in day-to-day use. Let's take a look at some of them.
+
+### String Interpolation
+
+The most used f-string feature by far is string interpolation. All you need to do is wrap the value or variable in curly braces (`{}`) and you're good to go.
+
+```py
+str_val = 'apples'
+num_val = 42
+
+print(f'{num_val} {str_val}') # 42 apples
+```
+
+### Variable names
+
+Apart from getting a variable's value, you can also get its name alongside the value. This can be especially useful when debugging and can be easily accomplished by adding an equals sign (`=`) after the variable name inside the curly braces.
+
+Bear in mind that whitespace inside the curly braces is taken into account, so adding spaces around the equals sign can make for a more readable result.
+
+```py
+str_val = 'apples'
+num_val = 42
+
+print(f'{str_val=}, {num_val = }') # str_val='apples', num_val = 42
+```
+
+### Mathematical operations
+
+Not syntactically unlike variable names, you can also perform mathematical operations in f-strings. You can place the mathematical expression inside the curly braces and, if you add an equal sign, you'll get the expression and its result.
+
+```py
+num_val = 42
+
+print(f'{num_val % 2 = }') # num_val % 2 = 0
+```
+
+### Printable representation
+
+Apart from plain string interpolation, you might want to get the printable representation of a value. This is already easy to accomplish using the `repr()` function. f-strings provide a much shorter syntax by appending a `!r` inside the curly braces.
+
+```py
+str_val = 'apples'
+
+print(f'{str_val!r}') # 'apples'
+```
+
+### Number formatting
+
+Additionally, f-strings can also be used for formatting - hence the **f** in the name. To add formatting to a value you can add a colon (`:`) followed by a format specifier. This can also be combined with the equals sing from before, shall you want to print the name of the variable as well.
+
+Numbers are a great candidate for this. If, for example, you want to trim a numeric value to two digits after the decimal, you can use the `.2f` format specifier.
+
+```py
+price_val = 6.12658
+
+print(f'{price_val:.2f}') # 6.13
+```
+
+### Date formatting
+
+Finally, dates can also be formatted the same way as numbers, using format specifiers. As usual, `%Y` denotes the full year, `%m` is the month and `%d` is the day of the month.
+
+```py
+from datetime import datetime;
+
+date_val = datetime.utcnow()
+
+print(f'{date_val=:%Y-%m-%d}') # date_val=2021-07-09
+```