Python编写数值转DOB程序触发int()转换类ValueError报错求助

你遇到的ValueError: invalid literal for int() with base 10: <日值>完全是代码逻辑顺序颠倒导致的：
你在做日期范围合法性校验之前，就已经把原始输入的纯数字日值拼接了st/nd/rd/th这类文本后缀。比如用户输入日值1，经过那串if判断后，day变量的值已经从纯字符串"1"变成了带字母内容的"1st"。后续校验逻辑里直接执行int(day)做数值比较时，Python无法把夹杂字母的字符串转为合法整数，自然触发转换报错。

• 调整代码执行顺序：把原本提前做的日值后缀拼接逻辑，整体移动到合法性校验完成之后执行
• 做范围判断时，使用用户最开始输入的、未经过后缀拼接的原始纯数字日值做整数转换和数值对比，避免用带字母后缀的字符串转整数
• 只有当日值通过合法性校验后，再按照规则拼接对应后缀生成最终用于展示的日期格式

uy = input("Enter your birth year: ")
um = input("Enter the number of your birth month (1-12): ")
mn_list = ["January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"]
# 月份映射逻辑可直接通过列表索引取值，减少冗余判断
mn = mn_list[int(um)-1] if um.isdigit() and 1<=int(um)<=12 else ""
day_raw = input("please enter the day number of the date (1-31): ")

# 先判断输入是否为合法数字，避免非数字内容触发转整数报错
if not day_raw.isdigit():
    print("The data entered was not valid, please try again.")
else:
    day_num = int(day_raw)
    # 用纯数字原始值做合法性校验
    if mn == "February" and day_num <= 28:
        vd = True
    elif (mn == "April" or mn == "June" or mn == "September" or mn == "November") and day_num <= 30:
        vd = True
    elif mn in ["January", "March", "May", "July", "August", "October", "December"] and day_num <= 31:
        vd = True
    else:
        vd = False

    if vd:
        # 校验通过后再做后缀拼接
        if day_num in (1,21,31):
            day_display = day_raw + "st"
        elif day_num in (2,22):
            day_display = day_raw + "nd"
        elif day_num in (3,23):
            day_display = day_raw + "rd"
        else:
            day_display = day_raw + "th"
        print(f"Your date of birth is the {day_display} {mn} {uy}")
    else:
        print("The data entered was not valid, please try again.")

• 当前2月的校验逻辑固定判定最大日值为28，没有覆盖闰年2月29天的合法场景，后续可以加闰年判断逻辑兼容这类情况
• 原有月份映射写了12个连续if/elif分支，通过列表索引直接取值可以大幅减少冗余代码

内容的提问来源于stack exchange，提问作者OAK1000101