如何让Python代码仅接收整数输入并执行正确数值比较？

原代码存在两个核心问题：

• 直接对输入的字符串与字符串形式的数字做字典序比较，而非数值比较（例如'10' < '2'会返回True，完全不符合逻辑）
• 未校验输入是否为有效整数，非数字输入会导致错误的比较结果或异常

修改后的代码（基础版） #

while True:
    try:
        applesToday = int(input("Hope you're having a nice day! How many apples have you eaten?"))
        break
    except ValueError:
        print("Please enter a valid whole number.")

if applesToday == 1:
    print("You've had 1 apple")
elif applesToday == 0:
    print("You've had 0 apples")
else:
    print(f"You've had {applesToday} apples")

关键改动说明 #

• 输入校验与类型转换：通过while True循环+try-except捕获ValueError，强制用户输入有效整数——若输入无法转为整数（如字母、小数），则提示重新输入，直到得到合法值
• 数值比较替代字符串比较：将输入转为整数后，直接与整数进行数值比较，逻辑准确且直观
• 简化输出逻辑：使用f-string简化格式化输出，同时明确区分单复数表述（1个用apple，其他用apples）

进阶优化：限制非负整数 #

如果需要确保输入的苹果数量为非负数（更符合实际场景），可以在转换后增加额外判断：

while True:
    try:
        applesToday = int(input("Hope you're having a nice day! How many apples have you eaten?"))
        if applesToday >= 0:
            break
        else:
            print("Please enter a non-negative number.")
    except ValueError:
        print("Please enter a valid whole number.")

if applesToday == 1:
    print("You've had 1 apple")
elif applesToday == 0:
    print("You've had 0 apples")
else:
    print(f"You've had {applesToday} apples")

内容的提问来源于stack exchange，提问作者Soto