Python ord Function

Last modified April 11, 2025

This comprehensive guide explores Python's ord function, which returns the Unicode code point of a character. We'll cover ASCII values, Unicode handling, and practical examples of character encoding.

Basic Definitions

The ord function returns an integer representing the Unicode code point of a character. It's the inverse of chr function.

Key characteristics: accepts a single character string (length 1), returns an integer between 0 and 1,114,111 (0x10FFFF in base 16). Raises TypeError for invalid inputs.

Basic ASCII Usage

Here's simple usage with ASCII characters showing how ord returns their numeric values.

basic_ord.py

# Uppercase letters
print(ord('A'))  # 65
print(ord('B'))  # 66

# Lowercase letters
print(ord('a'))  # 97
print(ord('b'))  # 98

# Digits
print(ord('0'))  # 48
print(ord('9'))  # 57

# Special characters
print(ord(' '))  # 32 (space)
print(ord('!'))  # 33

This example shows ord with common ASCII characters. The values match standard ASCII encoding where 'A' is 65, 'a' is 97, and '0' is 48.

Note that uppercase and lowercase letters have different code points, with lowercase letters having higher values than their uppercase counterparts.

Unicode Characters

ord works with any Unicode character, not just ASCII. This example demonstrates with various Unicode symbols.

unicode_ord.py

# Common symbols
print(ord('€'))  # 8364 (Euro sign)
print(ord('¥'))  # 165 (Yen sign)

# Emoji
print(ord('😊')) # 128522 (Smiling face)

# Chinese character
print(ord('中')) # 20013

# Mathematical symbols
print(ord('∑'))  # 8721

These examples show ord with Unicode characters beyond ASCII. The function returns their unique code points in the Unicode standard.

This demonstrates Python's full Unicode support, where each character has a unique numeric identifier regardless of language or symbol type.

Error Handling

The ord function raises TypeError when used incorrectly. This example shows common error cases.

errors.py

try:
    print(ord(''))  # Empty string
except TypeError as e:
    print(f"Error: {e}")  # ord() expected a character, but string of length 0 found

try:
    print(ord('ab'))  # String longer than 1 character
except TypeError as e:
    print(f"Error: {e}")  # ord() expected a character, but string of length 2 found

try:
    print(ord(65))  # Not a string
except TypeError as e:
    print(f"Error: {e}")  # ord() expected string of length 1, but int found

These examples demonstrate ord's strict input requirements. It only accepts single-character strings and rejects all other input types.

Proper error handling is important when processing user input that will be passed to ord to avoid program crashes.

Character Analysis

This example shows how ord can be used to analyze character properties like case, digit status, or special characters.

analysis.py

def char_info(c):
    code = ord(c)
    print(f"Character: {c}")
    print(f"Code point: {code}")
    print(f"Uppercase: {65 <= code <= 90}")
    print(f"Lowercase: {97 <= code <= 122}")
    print(f"Digit: {48 <= code <= 57}")
    print(f"Control char: {code < 32 or code == 127}")

char_info('A')
char_info('z')
char_info('5')
char_info('\n')

This function uses ord to get a character's code point and then checks various ranges to determine its properties.

Such analysis is useful for text processing, validation, or implementing custom character classification logic beyond Python's built-in methods.

Custom Encoding Conversion

This example demonstrates using ord to convert text to custom numeric representations.

encoding.py

def text_to_codes(text, base=16):
    return [hex(ord(c)) if base == 16 else str(ord(c)) for c in text]

print(text_to_codes("Hello"))  # ['0x48', '0x65', '0x6c', '0x6c', '0x6f']
print(text_to_codes("Python", 10))  # ['80', '121', '116', '104', '111', '110']

def create_cipher_key(text):
    return {c: ord(c) * 2 for c in text}

print(create_cipher_key("secret"))  # {'s': 230, 'e': 202, 'c': 198, 'r': 216, 't': 232}

The first function converts text to hexadecimal or decimal code points. The second creates a simple cipher key by doubling each character's value.

These examples show practical applications of ord in text processing, encoding, and simple cryptography operations.

Best Practices

Validate input length: Ensure strings are length 1 before passing to ord
Combine with chr: Use ord/chr pairs for character transformations
Handle Unicode: Remember ord works with all Unicode characters
Document encoding: Clarify if working with ASCII or Unicode values
Error handling: Catch TypeError when processing unknown input

Source References

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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