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80 lines
2 KiB
Text
80 lines
2 KiB
Text
/**
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@page working_with_dates Working with Dates and Times
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Dates and times in Excel are represented by real numbers. For example a date
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that is displayed in Excel as "Jan 1 2013 12:00 PM" is stored as the number
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41275.5.
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The integer part of the number stores the number of days since the epoch,
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which is generally 1900, and the fractional part stores the percentage of the
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day.
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A date or time in Excel is just like any other number. To display the number
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as a date you must apply an Excel number format to it. Here is an example:
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@dontinclude dates_and_times01.c
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@skip include
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@until return
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@until }
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@image html date_example01.png
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To make working with dates and times a little easier the `libxlsxwriter`
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library provides the lxw_datetime struct and the worksheet_write_datetime()
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function.
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The members of the lxw_datetime struct and the range of their values are:
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Member | Value
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-------- | -----------
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year | 1900 - 9999
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month | 1 - 12
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day | 1 - 31
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hour | 0 - 23
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min | 0 - 59
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sec | 0 - 59.999
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Dates in Excel do not support timezones and the maximum resolution of times is
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milliseconds.
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If dates or times are required without the other you should initialize the
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unrequired values to `0`:
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@code
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// Date and time.
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lxw_datetime datetime1 = {2014, 11, 25, 17, 45, 5.1};
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// Date only.
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lxw_datetime datetime2 = {2014, 11, 25, 0, 0, 0};
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// Time only.
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lxw_datetime datetime3 = {0, 0, 0, 17, 45, 5.1};
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@endcode
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Using lxw_datetime and worksheet_write_datetime() the previous example can
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then be re-written as follows:
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@dontinclude dates_and_times02.c
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@skip include
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@until return
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@until }
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The output from this program is the same as the previous example.
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@image html date_example02.png
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Dates can be formatted using any of the date formats supported by Excel. Here
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is a longer example that shows the same date in a several different formats:
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@dontinclude dates_and_times03.c
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@skip include
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@until return
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@until }
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@image html date_example03.png
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Next: @ref working_with_charts
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*/
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