使用分隔符的日期验证作业实现技术咨询

Hey there! Building this date validator/formatter is totally doable with a structured approach. Let's walk through how to tackle it step by step, including a practical code example since it's great for this kind of text and date handling.

First, let's make sure we're aligned on what needs to be done:

• Accept flexible input formats: days as dd, d, or 0d; months as mm, m, 0m, or case-insensitive 3-letter abbreviations (e.g., Jan, jul, FEB)
• Validate the date: flag invalid entries with a clear reason (like "年份超出范围" or "日期超出当月范围")
• Format valid dates to the exact dd Mmm yyyy style (e.g., 01 Apr 1882)

1. Set Up Month Mapping #

We need two-way mappings to handle both numeric and text month inputs, and to format the output correctly:

• Map 3-letter month abbreviations (case-insensitive) to numeric values
• Map numeric months back to capitalized abbreviations for the final output

2. Parse & Validate Each Component #

Break the input string into day, month, year, then validate each part:

• Year: Convert to integer and check if it falls within your required range (the example shows 3062 is invalid, so define min_year and max_year based on your assignment specs)
• Month: First try converting to an integer (to handle 03, 3, etc.). If that fails, normalize the input to lowercase, take the first 3 characters, and look it up in our abbreviation map. If neither works, the month is invalid.
• Day: Convert to integer, then check if it's valid for the given month and year (account for 30-day months, February's leap year rules)

3. Format or Return Error #

If all checks pass, format the day to two digits, use the capitalized month abbreviation, and output the full date. If any check fails, return the input string with a clear "INVALID" message.

Here's a function that puts all this together:

def validate_and_format_date(input_str):
    # Map 3-letter month abbreviations (lowercase) to numeric values
    month_abbr_to_num = {
        "jan": 1, "feb": 2, "mar": 3, "apr": 4, "may": 5, "jun": 6,
        "jul": 7, "aug": 8, "sep": 9, "oct": 10, "nov": 11, "dec": 12
    }
    # Reverse mapping for formatted output (numeric month → capitalized abbreviation)
    num_to_month_abbr = {v: k.title() for k, v in month_abbr_to_num.items()}
    # Adjust these based on your assignment's year range requirements
    MIN_YEAR = 1882
    MAX_YEAR = 3061

    try:
        # Split input into day, month, year (strip extra whitespace first)
        day_str, month_str, year_str = input_str.strip().split()

        # Validate year
        year = int(year_str)
        if not (MIN_YEAR <= year <= MAX_YEAR):
            return f"{input_str} - INVALID: 年份超出范围"

        # Validate month
        month = None
        # Try numeric month first (handles 03, 3, 012? Wait no—int("012") becomes 12, which is valid)
        try:
            month = int(month_str)
            if not 1 <= month <= 12:
                return f"{input_str} - INVALID: 月份无效"
        except ValueError:
            # Fall back to abbreviation matching
            normalized_abbr = month_str.lower()[:3]
            month = month_abbr_to_num.get(normalized_abbr)
            if month is None:
                return f"{input_str} - INVALID: 月份无效"

        # Validate day
        day = int(day_str)
        # Determine max days for the given month/year
        if month in [4, 6, 9, 11]:
            max_day = 30
        elif month == 2:
            # Leap year check: divisible by 4, not by 100 unless also by 400
            is_leap = (year % 4 == 0 and year % 100 != 0) or (year % 400 == 0)
            max_day = 29 if is_leap else 28
        else:
            max_day = 31

        if not 1 <= day <= max_day:
            return f"{input_str} - INVALID: 日期超出当月范围"

        # Format valid date to required style
        formatted_day = f"{day:02d}"
        formatted_month = num_to_month_abbr[month]
        return f"{formatted_day} {formatted_month} {year}"

    except ValueError:
        # Catch cases where input isn't split into 3 parts, or non-numeric day/year
        return f"{input_str} - INVALID: 输入格式不正确"

Let's run through some examples to make sure it works:

• Input: 03 JUL 3062 → Output: 03 JUL 3062 - INVALID: 年份超出范围
• Input: 1 apr 1882 → Output: 01 Apr 1882
• Input: 29 Feb 2023 → Output: 29 Feb 2023 - INVALID: 日期超出当月范围
• Input: 05 09 2000 → Output: 05 Sep 2000
• Input: 31 04 2024 → Output: 31 04 2024 - INVALID: 日期超出当月范围

• Adjust MIN_YEAR and MAX_YEAR to match your assignment's exact requirements
• If your input might use other separators (like / or .), add a step to replace them with spaces before splitting
• The function handles extra whitespace around the input thanks to strip()

内容的提问来源于stack exchange，提问作者user2930414