overlap | 易学教程

Checking a table for time overlap?

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问题 I have a MySQL table with the following fields: name starttime endtime starttime and endtime are MySQL TIME fields (not DATETIME ). I need a way to periodically \"scan\" the table to see if there are any overlaps in time ranges within the table. If there is an event from 10:00-11:00 and another from 10:30-11:30 , I want to be alerted of the presence of the time overlap. Nothing fancy really, all I want to know whether an overlap exists or not. I\'m going to be using PHP to execute this. 回答1:

Overlapping matches in Regex

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I can't seem to find an answer to this problem, and I'm wondering if one exists. Simplified example: Consider a string "nnnn", where I want to find all matches of "nn" - but also those that overlap with each other. So the regex would provide the following 3 matches: nn nn n nn n nn nn I realize this is not exactly what regexes are meant for, but walking the string and parsing this manually seems like an awful lot of code, considering that in reality the matches would have to be done using a pattern, not a literal string. VonC A possible solution could be to use a positive look behind : (?<=n)n

Why the content is not covered by the background of an overlapping element?

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问题 Here is the situation: body { margin: 0; background: pink; color: #fff; } .box { margin-top: 20px; background: red; } .bottom { text-align: right; background: green; animation: animate 2s infinite alternate linear; } @keyframes animate { from { margin-top: 10px; } to { margin-top: -40px; } } <div class=\"box\"> some content </div> <div class=\"bottom\"> other content </div> What\'s happening? As you may see we have two div without any complex styling (simply background-color). I am making the

Is it a bad practice to use negative margins in Android?

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问题 Demo of negative margin: The scenario Overlapping views by setting a negative margin to one of them so that it invades the bounding box of another view. Thoughts It seems to work the way you\'d expect with overlapping of the layouts if they should. But I don\'t want to run into a bigger problem for unknowingly not doing things right. Emulators, physical devices, you name it, when you use negative margins everything seems to work correctly, one view invades another\'s views bounding box and

Determine if two rectangles overlap each other?

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问题 I am trying to write a C++ program that takes the following inputs from the user to construct rectangles (between 2 and 5): height, width, x-pos, y-pos. All of these rectangles will exist parallel to the x and the y axis, that is all of their edges will have slopes of 0 or infinity. I\'ve tried to implement what is mentioned in this question but I am not having very much luck. My current implementation does the following: // Gets all the vertices for Rectangle 1 and stores them in an array ->