Python中not in操作符使用问题：原色输入错误提示异常

我想要实现仅当输入不是原色（red、blue、yellow）时显示错误提示，但当前代码无论输入内容是什么，都会针对第一个和第二个颜色显示错误提示。我已尝试使用not in []和布尔值（color1 = False），问题仍未解决，相关代码如下：

color1 = input("Enter your first color (red, blue, yellow):").lower()
color2 = input("Enter your second color (red, blue, yellow):").lower()

    if (color1 == "red" and color2 == "blue") or (color1 == "blue" and color2 == "red"):
        print("Your result is purple")
    elif (color1 == "red" and color2 == "yellow") or (color1 == "yellow" and color2 == "red"):
        print("Your result is orange")
    elif (color1 == "blue" and color2 == "yellow") or (color1 == "yellow" and color2 == "blue"):
        print("Your result is green")

    if color1 not in ["red" "blue" or "yellow"]:
        print("Error: The first color you entered is invalid.")
    elif color2 not in ["red" "blue" or "yellow"]:
        print("Error: The second color you entered is invalid.")
    elif color1 == color2:
        print("Error: The two colors you entered are the same.")

核心问题点 #

• 列表语法错误：["red" "blue" or "yellow"] 是无效写法。字符串之间必须用逗号分隔，且or不能放在列表内部，正确的原色列表应为["red", "blue", "yellow"]。原写法会导致Python解析逻辑混乱，使not in判断永远为真，因此无论输入什么都会触发错误提示。
• 逻辑判断顺序错误：错误判断使用elif会导致，若第一个颜色有效则直接跳过第二个颜色的无效检查；颜色相同的判断放在最后，也会被前面的elif逻辑跳过，无法正常触发。

修正后的代码 #

# 定义原色列表，避免重复编写
primary_colors = ["red", "blue", "yellow"]

color1 = input("Enter your first color (red, blue, yellow):").lower()
color2 = input("Enter your second color (red, blue, yellow):").lower()

# 先处理所有错误情况
is_valid = True
if color1 not in primary_colors:
    print("Error: The first color you entered is invalid.")
    is_valid = False
if color2 not in primary_colors:
    print("Error: The second color you entered is invalid.")
    is_valid = False
if color1 == color2:
    print("Error: The two colors you entered are the same.")
    is_valid = False

# 仅当输入完全有效时，执行颜色混合逻辑
if is_valid:
    if (color1 == "red" and color2 == "blue") or (color1 == "blue" and color2 == "red"):
        print("Your result is purple")
    elif (color1 == "red" and color2 == "yellow") or (color1 == "yellow" and color2 == "red"):
        print("Your result is orange")
    elif (color1 == "blue" and color2 == "yellow") or (color1 == "yellow" and color2 == "blue"):
        print("Your result is green")

修复说明 #

1. 提取primary_colors统一管理原色列表，提升代码可读性和维护性。
2. 独立判断每个错误条件，确保所有无效输入都能被检测并提示。
3. 用is_valid标记输入状态，仅在输入完全合法时才执行颜色混合逻辑，避免无效输入进入正常流程。

内容的提问来源于stack exchange，提问作者Becca