Python中检查整数奇偶性：二进制末位判断的常见陷阱与优化实践

def any_odd(x):
    x_bin_str = str(bin(x)) # 将整数转换为二进制字符串，例如 '0b101'
    # 尝试比较二进制字符串的末位字符与整数1
    return True if x_bin_str[-1] == 1 else False

print('1' == 1) # 输出: False

def is_odd_by_binary_string_fixed(x):
    x_bin_str = bin(x) # bin() 函数本身就返回字符串，无需再次str()
    return True if x_bin_str[-1] == "1" else False

# 示例
print(f"is_odd_by_binary_string_fixed(5): {is_odd_by_binary_string_fixed(5)}") # 输出: True
print(f"is_odd_by_binary_string_fixed(4): {is_odd_by_binary_string_fixed(4)}") # 输出: False

def is_odd_by_binary_string_pythonic(x):
    x_bin_str = bin(x)
    return x_bin_str[-1] == "1"

# 示例
print(f"is_odd_by_binary_string_pythonic(5): {is_odd_by_binary_string_pythonic(5)}") # 输出: True
print(f"is_odd_by_binary_string_pythonic(4): {is_odd_by_binary_string_pythonic(4)}") # 输出: False

def is_odd_bitwise(x):
    return (x & 1) == 1

# 或者更简洁地利用Python中0为False，非0为True的特性
def is_odd_bitwise_pythonic(x):
    return bool(x & 1)

# 示例
print(f"is_odd_bitwise(5): {is_odd_bitwise(5)}")             # 输出: True
print(f"is_odd_bitwise(4): {is_odd_bitwise(4)}")             # 输出: False
print(f"is_odd_bitwise_pythonic(5): {is_odd_bitwise_pythonic(5)}") # 输出: True
print(f"is_odd_bitwise_pythonic(4): {is_odd_bitwise_pythonic(4)}") # 输出: False

def is_odd_modulo(x):
    return x % 2 != 0

# 示例
print(f"is_odd_modulo(5): {is_odd_modulo(5)}") # 输出: True
print(f"is_odd_modulo(4): {is_odd_modulo(4)}") # 输出: False