如何在凯撒密码中保持标点符号不变？- Python

def caesar_cipher(text, shift):
    encrypted_text = ""
    for char in text:
        if char.isalpha():
            if char.isupper():
                encrypted_text += chr((ord(char) - 65 + shift) % 26 + 65)
            else:
                encrypted_text += chr((ord(char) - 97 + shift) % 26 + 97)
        else:
            encrypted_text += char
    return encrypted_text

# 示例用法
plaintext = "Hello, World!"
shift = 3
ciphertext = caesar_cipher(plaintext, shift)
print("加密后的文本：", ciphertext)