Several common ways to convert strings to lowercase letters in Python

In Python, there are several ways to convert uppercase letters in a string to lowercase letters. Here are some commonly used methods:

1. Use the built-in method lower() (the easiest)

Python string objects come withlower()Method, you can directly convert all uppercase letters to lowercase, and other characters remain unchanged.

Sample code：

s = "Hello, WORLD!"
result = ()
print(result)  # Output: "hello, world!"

2. Manual traversal + ASCII code conversion

You can traverse each character in a string and use the ASCII code value (ord()andchr()) Manually convert capital letters (A-Z's ASCII range is 65-90).

Sample code：

s = "Hello, WORLD!"
result = ""
for char in s:
    if 65 <= ord(char) <= 90:  # Check if it is capital letters        result += chr(ord(char) + 32)  # uppercase to lowercase (ASCII difference is 32)    else:
        result += char
print(result)  # Output: "hello, world!"

3. Use () (performance optimization)

pass()Create a conversion table and use ittranslate()Methods batch replace characters, suitable for processing large amounts of text.

Sample code：

s = "Hello, WORLD!"
# Create a conversion table: Map A-Z to a-ztrans_table = ('ABCDEFGHIJKLMNOPQRSTUVWXYZ', 
                           'abcdefghijklmnopqrstuvwxyz')
result = (trans_table)
print(result)  # Output: "hello, world!"

4. Use list comprehension (concise writing method)

Combinedchr()andord(), generate a new string using list comprehension.

Sample code：

s = "Hello, WORLD!"
result = ''.join(
    chr(ord(c) + 32) if 'A' <= c <= 'Z' else c
    for c in s
)
print(result)  # Output: "hello, world!"

Summarize

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