I'm using wxWidgets to write cross-plafrom applications. In one of applications I need to be able to load data from Microsoft Excel (.xls) files, but I need this to work on Linux as well, so I assume I cannot use OLE or whatever technology is available on Windows.
I see that there are many open source programs that can read excel files (OpenOffice, KOffice, etc.), so I wonder if there is some library that I could use?
Excel files it needs to support are very simple, straight tabular data. I don't need to extract any formatting except column/row position and the data itself.
Suggestedd reference: What is a simple and reliable C library for working with Excel files?
I came across other libraries (chicago on sf.net, xlsLib) but they seem to be outdated.
jrh
I can say that I know of a wxWidgets application that reads Excel .xls and .xlsx files on any platform. For the .xlsx files we used an XML parser and zip stream reader and grab the data we need, pretty easy to get going. For the .xls files we used: ExcelFormat, which works well and we found the author to be very generous with his support.
Maybe just some encouragement to give it a go? It was a couple of days work to get working.
Maybe http://www.libxl.com/ can help ?
I think that it is not something easy to do. xls files are quite complex and it is a proprietary format.
Maybe this is a stupid idea but why don't you upload and access your doc with Google docs. There are some apis to access your doc.
2 potential problems:
- Your app needs internet access
- Currently there is no C++ api.
But there are api for several languages including python see http://code.google.com/intl/fr/apis/gdata/articles/python_client_lib.html
Related
Basically, I want to be to be able to pass data between Excel cells and
my C++ program. I don't have any experience in Excel/C++ interactions and I haven't been able to find a coherent explanation or documentation on any websites. If someone could link me some references or provide one themselves it would be much appreciated. Thanks.
If this is for a Windows system, you could always use one of the available managed Excel libraries, such as OfficeWriter or Aspose.
There also might be similar libraries specifically for c++, I know we (OfficeWriter) used to make one.
Edit: Looks like there are a few out there, like LibXL and BasicExcel.
If the application will run on an end user machine with Excel installed, you can easily use the Excel interop and keep Excel hidden.
In addition to LibXL and BasicExcel mentioned by smoore, there is:
ExcelFormat Library is an improved version of the BasicExcel library and will allow you to read and write simple values. It is free.
xlslib will also read and write simple values, I have not tried it tho. It is also free.
Number Duck, is a commercial library that I have written, It supports reading and writing values, formulas and pictures. The website has examples of how to use the features.
I have seen programs exporting to Excel in two different ways.
Opening Excel and entering data cell by cell (while it is running it looks like a macro at work)
Creating an Excel file on disk and writing the data to the file (like the Export feature in MS Access)
Number 1 is terribly slow and to me it is just plain aweful.
Number 2 is what I need to do. I'm guessing I need some sort of SDK so that I can create Excel files in C++.
Do I need different SDKs for .xls and .xlsx?
Where do I obtain these? (I've tried Googling it but the SDKs I've found looks like they do other things than providing an interface to create Excel files).
When it comes to the runtime, is MS Office a requirement on the PC that needs to create Excel files or do you get a redistributable DLL that you can deploy with your executable?
You can easily do that by means of the XML Excel format. Check the wikipedia about that:
http://en.wikipedia.org/wiki/Microsoft_Excel#XML_Spreadsheet
This format was introduced in Excel 2002, and it is an easy way to generate a XLS file.
You can also try working with XLS/XLSX files over ODBC or ADO drivers just like databases with a limited usage. You can use some templates if you need formatting or create the files from stratch. Of course you are limited by playing with the field values that way. For styling etc. you will need to use an Excel API like Microsoft's.
I'm doing this via Wt library's WTemplate
In short, I created the excel document I wanted in open office, and save-as excel 2003 (.xml) format.
I then loaded that in google-chrome to make it look pretty and copied it to the clipboard.
Now I'm painstakingly breaking it out into templates so that Wt can render a new file each time.
I was wondering how difficult it would be to make an application like this. Basically, I have some old html files that use tables. I want to put these tables into excel for easier reading and manipulation. I only have text, I have no numbers of formulas or anything.
Are there any tutorials on how to do this sort of thing?
The application would produce .xls
Thanks
You have three options:
Output a CSV file. While not an XLS file, Excel is more than capable of opening such a file, and it's extremely easy to create. You need nothing more than standard C++ to implement this solution. This is by far the easiest and quickest way to output to Excel (or any spreadsheet program, for that matter).
Use OLE automation. Microsoft even has a Knowledge Base article that provides an example of how to invoke Excel from your native C++ application and fill in some values. If you absolutely need to output XLS files, this is the easiest way to go. Note that users must have Excel installed on their computers for this to work.
Create your own XLS writer. Don't even bother with this option unless you really want to generate XLS files without requiring Excel to be installed on end-user computers. Options 1 and 2 are more than good enough for just about any application.
You don't need to reverse-engineer the XLS format; Microsoft documents the excel file format here. Due to the evolution of Excel over the years, it's not exactly a clean specification.
If you don't mind installing a copy of Excel along with your program, using OLE Automation would be much easier.
The simplest thing to do is simply create a CSV file. If you have column headers, put them in the first row. CSV files can be opened natively in Excel as if they were Excel spreadsheets.
There is a trick here: save .html tables with the .xls extension and Excel can read them (ie Excel can read the output of the DataGrid control).
But, if you want to create 'real' Excel files, then you can either use Excel Interop (which could be messy, requires Excel and the PIA's to be installed on the machine, and needs careful memory management (since its COM)). You could also opt for a 3rd-party library like FlexCel - which will avoid many of the InterOp problems but will not give you 'complete' Excel functionality (addins, custom vba macros etc.). For most uses, however, a 3rd party library should do the trick.
Looks like there's another alternative called ExcelFormat. I didn't try it, though.
Could anyone please provide me a sample C/C++ code to read and edit PDF Metadata?
If it is XMP, what else to do?
If it's XMP, I think there's an SDK available from Adobe. But beware, PDF metadata has a long history and isn't only stored in XMP.
You might best be off using a library that allows PDF manipulation. There are several commercial ones available. I have no idea whether there's something usable available for free.
https://github.com/hfiguiere/exempi -- C-library to read and write XMP.
The XMP SDK from adobe does not read/write metadata of PDF files. PDF reading/writing is a complicated task. Your best bet is to use a third party PDF library, or commands like pdfleo.
If you haven't tried XMPToolkit yet, give it a shot and see if it meets your needs.
How to read/write data into excel 2007 in c++?
Excel provides COM interface which you can use from your C++ application.
I have experience with Excel 2003 only but I think for excel 2007 it will also work.
This can be done e.g. with #import or in the way described in this article:
http://support.microsoft.com/kb/216686
There is a python solution (using COM dispatch) here: http://snippets.dzone.com/posts/show/2036
It's not C++, but the COM interface should be the same no matter which language you use, right?
You wouldn't need to port everything. Just __init__, set_range, get_value, set_value, save (or save_as), close, and quit. You might also need to dispose of garbage (as python has automatic gc).
Or you could just port (and modify) the following code (which I haven't tested, as I don't have excel anymore - you should probably check it by downloading python and pythonwin):
from win32com.client import Dispatch
app = Dispatch("Excel.Application")
app.Visible = True # spooky - watch the app run on your desktop!
app.Workbooks.Open("C:\\book.xls")
range = app.ActiveWorkbook.Sheets(1).Range("a1")
print 'The range was:'
print range.Value
range.Value = 42
print 'The value is now 42'
app.ActiveWorkbook.Save()
app.ActiveWorkbook.SaveAs("C:\\excel2.xls")
app.ActiveWorkbook.Close()
app.Quit()
# any gc to do?
Excel 2007 files are simply zip files. Try to rename .xlsx to .zip: you can extract files and folders. With a text editor you can view that they are all XML files.
So the solution:
use a common class to unzip your xlsx
use an xml parser to grab you data
if you have modified somethig, re-zip all
No COM object required.
Depending on your c++ compiler you can easyly find the required sources.
There are three main things you need to do.
1) Ensure pre-requisite files are installed and locatable.
Blindingly obvious I know, but make sure you have a suitable version of Excel installed, so that you can locate the required Microsoft libraries (and their locations).
namely MSO.DLL, VBE6EXT.OLB and EXCEL.EXE
2) Set up the Microsoft libraries.
In your C++ code, let's say you start with a simple console application, be sure to include the import libraries in any C++ application that interfaces with Excel. In my example I use:
#import "C:\\Program Files (x86)\\Common Files\\microsoft shared\\OFFICE11\\MSO.DLL" \
rename( "RGB", "MSORGB" )
using namespace Office;
#import "C:\\Program Files (x86)\\Common Files\\microsoft shared\\VBA\\VBA6\\VBE6EXT.OLB"
using namespace VBIDE;
#import "C:\\Program Files (x86)\\Microsoft Office\\OFFICE11\\EXCEL.EXE" \
rename( "DialogBox", "ExcelDialogBox" ) \
rename( "RGB", "ExcelRGB" ) \
rename( "CopyFile", "ExcelCopyFile" ) \
rename( "ReplaceText", "ExcelReplaceText" ) \
exclude( "IFont", "IPicture" ) no_dual_interfaces
3) Use the Excel Object Model in your C++ code
For example, to declare an Excel Application Object pointer for reading / writing an Excel Workbook:
Excel::_ApplicationPtr pXL;
pXL->Workbooks->Open( L"C:\\dump\\book.xls" );
And to access and manipulate the Excel Worksheet and the cells within it:
Excel::_WorksheetPtr pWksheet = pXL->ActiveSheet;
Excel::RangePtr pRange = pWksheet->Cells;
double value = pRange->Item[1][1];
pRange->Item[1][1] = 5.4321;
And so on. I have a more in-depth discussion at this following blog posting.
A low tech way I have used on a couple of projects is to make a simple script/macro/whatever that runs an external program. Write that external program in C++. Get that external program to read its input from and write its output to a .csv file (simple comma separated value text file). Excel can easily read and write .csv files, so this setup gives you everything you need to craft a viable solution.
This can all be done via the IDispatch interface. It can get really bloody complicated quickly (Cheers Microsoft) but at least once you've got your head round Excel you'll find integrating with any other MS application easy too :)
Fortunately there is someone over on codeguru who has made the process nice and easy. Once I'd read through that code I started to get my head round what excel was doing and, furthermore, i found it became REALLY easy to extend it to do other things that I wanted. Just remember that you are sending commands to Excel via the IDispatch interface. This means you need to think about how YOU would do something to figure out how to do it programatically.
Edit: the code guru example is for Excel 2003 but it should be fairly easy to extend it to 2007 :)
Start here with the OpenXml Sdk. Download the SDK from here. The SDK uses .NET, so you might need to use C++.NET
It has been a very long time but I have used the Jet OLEDB to get at Excel files. You might start searching in that direction.
I have used a 3rd Party component for this in the past: OLE XlsFile from SM Software (not free, but inexpensive). The advantage of this component over the Microsoft COM components is that you can use it to write XLS files even if Excel is not installed.
It also allows you to create speadsheets or workbooks with embedded formulas and formatting, something not possible if you use CSV files as an interchange format.
If you need the best performance, writing binary Excel files is the way to go and writing them is not as difficult as reading them. The binary file format is relatively well documented by the OpenOffice.org project:
http://sc.openoffice.org/excelfileformat.pdf
and Microsoft has also released the documentation:
http://download.microsoft.com/download/0/B/E/0BE8BDD7-E5E8-422A-ABFD-4342ED7AD886/Excel97-2007BinaryFileFormat(xls)Specification.xps
This solution will work best if you have to write many Excel files, mostly with data and little formatting, and if you don't want to open the files at the same time. If you write a single Excel file to open it afterwards, you can probably use the propsed C++ COM Interface as the other posters have explained.
Using the COM interface will necessitate expensive out-of-process calls unless you write an Excel COM Addin. If you write an Addin that imports your data into the current Excel sheet, filling the sheet will still be much slower than dumping a file, but for a single file at a time this can be acceptable depending on your user scenario. If you do decide to use the COM interface, minimize the number of calls to Excel. Use the methods that allow to insert an array of values if they exist, set style properties by row and column is possible and not per cell.
You can use ODBC to read and write data from an excel file easily without Excel. The link:Here
The link for how to write data using odbc: Here
I've used a set of C++ classes that is available from CodeProject before to write to XLS files.
It's really easy to use, and free! You can find it here.
Took me no time to set up.