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format() | Python’s Built-in Functions – Real Python

The built-in format() function converts an input value into a formatted string representation based on the specified format. The function takes a format specification, format_spec, which determines how the value should be formatted:

format() Signature

Arguments

Argument Description Default Value
value The value to be formatted. Required argument
format_spec A string specifying the format using the mini-language syntax. ""

Return Value

  • Returns a formatted string representation of the input value according to the specified format.
  • If format_spec isn’t provided, then format() returns the string representation of the value as if str(value) was called.

format() Examples

With a floating-point number and a format specifier for two decimal places:

With an integer number and a format specifier for thousand separators:

With a string and a format specifier for left alignment and filling:

format() Common Use Cases

The most common use cases for the format() function include:

  • Formatting numbers for better readability, such as adding thousand separators or specifying decimal places.
  • Aligning text within a fixed width, using left, right, or center alignment.
  • Formatting dates and times in a specific format.
  • Preparing data for display in reports or user interfaces.

format() Real-World Example

Suppose you’re creating a financial report and need to format currency values consistently. Here’s how you can use the format() function to achieve that:

In this example, the format() function formats the sales amount with a comma as a thousand separator and two decimal places. Then, you add a dollar sign using an f-string. This helps present financial data clearly and professionally.

Python String Formatting: Available Tools and Their Features

For additional information on related topics, take a look at the following resources: