获取指定月份的所有周，每周从星期日到星期六。

以下是Python代码示例，用于获取指定月份的所有周，每周从星期日到星期六：

from datetime import datetime, timedelta

def get_weeks_in_month(year, month):
    # 获取指定月份的第一天
    start_date = datetime(year, month, 1)
    # 计算指定月份的下个月的第一天
    if month == 12:
        end_date = datetime(year + 1, 1, 1)
    else:
        end_date = datetime(year, month + 1, 1)
    # 计算指定月份的第一个星期天
    first_sunday = start_date + timedelta(days=(6 - start_date.weekday()))
    
    # 初始化结果列表
    weeks = []
    current_date = first_sunday
    # 循环生成每周的起始日期和结束日期
    while current_date < end_date:
        week_start = current_date
        week_end = current_date + timedelta(days=6)
        weeks.append((week_start, week_end))
        current_date += timedelta(days=7)
    
    return weeks

# 示例使用方法
year = 2021
month = 10
weeks = get_weeks_in_month(year, month)
for week_start, week_end in weeks:
    print(f"Week: {week_start.strftime('%Y-%m-%d')} - {week_end.strftime('%Y-%m-%d')}")

输出结果为：

Week: 2021-10-03 - 2021-10-09
Week: 2021-10-10 - 2021-10-16
Week: 2021-10-17 - 2021-10-23
Week: 2021-10-24 - 2021-10-30
Week: 2021-10-31 - 2021-11-06