日期范围与其他日期范围的重叠 [英] Overlap of a Date Range with Other Date Ranges

问题描述

晚上好，

我想弄清楚如何通过比较日期范围来计算日期范围之间的天数.例如，我有三个给定的范围:

I am trying to figure out how to count the number of days between date ranges by comparing the date ranges. For example, I have three given ranges:

range_1 01/01/2001 to 01/01/2002
range_2 01/02/2002 to 01/01/2003
range_3 01/02/2003 to 01/01/2004

如果我将 my_date_range 12/12/2001 和 01/05/2002 与上述范围进行比较，结果应该显示 range_1 和 my_date_range 之间有 19 天，range_2 和 my_date_range 之间有 5 天，range_3 和my_date_range 有 0 天.

If I compare my_date_range 12/12/2001 to 01/05/2002 with the ranges above, the result should show that between range_1 and my_date_range there are 19 days, between range_2 and my_date_range there are 5 days, and between range_3 and my_date_range there are 0 days.

在 Excel 中这很容易，我会简单地使用:

In Excel this was easy, I would simply use:

=SUMPRODUCT(ISNUMBER(MATCH(ROW(INDIRECT(A1&":"&B1)),ROW(INDIRECT($C$1&":"&$D$1)),0))*1)

其中 A1 和 B1 是用户输入的开始日期和结束日期，C1 和 D1 是三个日期范围之一.然后我会使用相同的公式并将 A1 和 B1 与第二个日期范围进行比较，然后是第三个.

where A1 and B1 are the start and end dates the user enters, and C1 and D1 is one of the three date ranges. I would then use the same formula and compare A1 and B1 to the second date range, then the third.

但是这怎么翻译成objective-c呢?(我能够比较两个日期并获得它们之间的天数.)

But how is this translated into objective-c? (I am able to compare two dates and get the number of days between them.)

推荐答案

首先，您必须将日期字符串转换为 NSDate 值:

First you have to convert the date strings to NSDate values:

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"MM/dd/yyyy"];

NSDate *range1Start = [dateFormatter dateFromString:@"01/01/2001"];
NSDate *range1End   = [dateFormatter dateFromString:@"01/01/2002"];

NSDate *userStart   = [dateFormatter dateFromString:@"12/12/2001"];
NSDate *userEnd     = [dateFormatter dateFromString:@"01/05/2002"];

然后你可以计算重叠间隔:

Then you can compute the overlapping interval:

NSDate *overlapFrom = [range1Start laterDate:userStart];
NSDate *overlapTo   = [range1End earlierDate:userEnd];

最后是重叠间隔的开始日期和结束日期之间的天数:

And finally the number of days between the start and end date of the overlapping interval:

NSInteger days;
if ([overlapFrom compare:overlapTo] > 0) {
    // Date ranges do not overlap
    days = 0;
} else {
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *comp = [calendar components:NSDayCalendarUnit fromDate:overlapFrom toDate:overlapTo options:0];
    days = [comp day];
}
NSLog(@"%ld", (long)days);

在此示例中，输出为 20，因为 12/12/2001 和 01/01/2002 之间的差异是 20 天.如果要计算重叠范围的开始和结束日期，则必须添加 1.

In this example, the output is 20, because the difference between 12/12/2001 and 01/01/2002 is 20 days. You have to add 1 if both start and end day of the overlapping range should be counted.

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