Converting Integers to Hexadecimal Strings in Python

Introduction

Hexadecimal representation is a common way to express integer values using base-16. This means each digit can represent values from 0 to 15, using the digits 0-9 and the letters A-F (or a-f) to represent 10-15. Converting integers to their hexadecimal string equivalent is a frequent task in computer science, especially when dealing with low-level data, memory addresses, or color codes. This tutorial explains how to perform this conversion in Python, covering different methods and formatting options.

Using the hex() Function

Python provides a built-in hex() function that directly converts an integer to its hexadecimal string representation. The resulting string will always be prefixed with "0x".

number = 255
hex_string = hex(number)
print(hex_string)  # Output: 0xff

The hex() function is straightforward and convenient for basic conversions. However, you might want to remove the "0x" prefix or control the formatting of the hexadecimal string.

Formatting Hexadecimal Strings

Python’s string formatting capabilities allow for more control over the output. Here are several ways to format hexadecimal strings:

Using f-strings (Formatted String Literals)

F-strings are a modern and readable way to embed expressions inside string literals. You can use them to format integers as hexadecimal strings with various options:

• Basic Hexadecimal: Use the :x or :X format specifier. :x produces lowercase hexadecimal digits, while :X produces uppercase.

  number = 15
  hex_string_lower = f'{number:x}'  # Output: f
  hex_string_upper = f'{number:X}'  # Output: F
  print(hex_string_lower)
  print(hex_string_upper)
  

• Padding with Zeros: Prefixing the format specifier with a number specifies the minimum width of the output, padding with zeros if necessary.

  number = 2034
  padded_hex = f'{number:0>4X}'  # Output: 07F2
  print(padded_hex)
  

  In this example, 0>4X means:

  • 0: Pad with zeros.
  • >: Right-align the output.
  • 4: Minimum width of 4 characters.
  • X: Use uppercase hexadecimal digits.

Using the % Operator (Old Style Formatting)

Although less preferred now, you can still use the % operator for string formatting:

number = 255
hex_string_lower = "%x" % number  # Output: ff
hex_string_upper = "%X" % number  # Output: FF
print(hex_string_lower)
print(hex_string_upper)

Using the format() Method

The format() method provides another way to format strings:

number = 15
hex_string_lower = '{:x}'.format(number) # Output: f
hex_string_upper = '{:X}'.format(number) # Output: F
print(hex_string_lower)
print(hex_string_upper)

Removing the "0x" Prefix

If you need the hexadecimal string without the "0x" prefix, you can easily slice the string returned by hex():

number = 255
hex_string_with_prefix = hex(number)  # Output: 0xff
hex_string_without_prefix = hex_string_with_prefix[2:]  # Output: ff
print(hex_string_without_prefix)

Character Representation

It’s important to distinguish between the string representation of a hexadecimal value and the character represented by that value. The chr() function can convert an integer representing a Unicode code point into its corresponding character:

code_point = 65  # ASCII for 'A'
character = chr(code_point)
print(character)  # Output: A

This is different from converting the integer 65 to its hexadecimal string representation (’41’).

Choosing the Right Method

• For simple conversions with the "0x" prefix, the hex() function is the most concise.
• For more control over formatting (padding, case, removing the prefix), f-strings or the format() method are preferred.
• If you’re working with legacy code, you might encounter the % operator for formatting.