Thread: How to read an Excel file

I have a work: that how to read an microsoft excel file.
For example: I have an excel file with multi sheets. (that I don't know what does these sheets' name). And my work is:
1) how to scan this file to find what sheets does it have and what's name.
2) after that, I want to read an exact cell that I want. for example: I want to read <programming sheet><cell A93>.

I think this work need a library to work, and I don't know it. I play with algorithm very much, but I never do something like that before. So, who can help me, please

thanks for all

Not sure how you would do this directly. However you can save excel files with a single sheet to .csv, which would convert a sheet that looks like this:

Code:

+---+---+
| 1 | 2 |
+---+---+
| 3 | 4 |
+---+---+

to a .csv file with these contents

Code:

1,2
3,4

For multiple sheets, you could write something in excel vba that would save each sheet to a separate .csv file, and then use your C++ program on those files. It's been a while since I used vba though, but I do know it's possible and fairly simple.

I have googled and see that there're some ways, but they have a same method: convert excel file to cvs file.
So, we cannot use excel file directly, huh :-?

Well, it must be possible, but I'm guessing it'd be pretty complex unless there's some library out there. Why do you want to use the excel file directly?

I have convert an excel file to cvs file, After open by notepad and see that, to express each cell, excel use "," this very hard to use algorithm to process these cells.
And, I google and no answer tell me how to convert excel file with multi sheets to multi cvs file by C++. So, who can help me, please

thanks

how to convert excel file with multi sheets to multi cvs file by C++.

You would probably be better off using Excel to export each sheet to a separate file. Trying to read an Excel file with C/C++ is difficult for several reasons. The first reason is that there are different versions of the file format depending on which version of Excel is being used.

I have convert an excel file to cvs file, After open by notepad and see that, to express each cell, excel use "," this very hard to use algorithm to process these cells.

Actually processing a Comma Separated Values file is fairly straight forward, as long as the actual data does not contain commas. Read the line with getline() to get the entire line into a std::string. Then using stringstreams use getline(), with the third parameter, or use the extraction operator<< to extract the data, using a throw away character to dispose of the comma.

If you feel you must convert the actual Excel file with C/C++ you may want to start by studying this: Excel File Format.

Jim

Originally Posted by jimblumberg

Actually processing a Comma Separated Values file is fairly straight forward, as long as the actual data does not contain commas. Read the line with getline() to get the entire line into a std::string. Then using stringstreams use getline(), with the third parameter, or use the extraction operator<< to extract the data, using a throw away character to dispose of the comma.

Wouldn't using getline directly with ',' specified as the delimiter be simpler ?

Wouldn't using getline directly with ',' specified as the delimiter be simpler ?

If you are trying to get numeric values you must still convert the string to the numeric values. Yes you can do all the processing on the file stream but I find string stream errors easier to handle than file stream errors, so I prefer to use getline() to get an entire line from the file then process that line using string streams.


Jim

a much better approach could be use some database library

Possibly, but in my opinion at the cost of much higher complexity. And no matter what the programmer must know what each data element represents.

Wonder how viable is pulling the whole thing into a string stream..and using >>s for getting the data..(and making a custom manipulator to ignore the comma)

Again, possible as long as the file size does not exceed the string stream maximum size. In my opinion using this method only becomes reasonable if profiling determines a need for a different approach, and then only if you are going to be parsing this data source quite often.

Jim

Originally Posted by hqt

Ohh, this make me sad and disappointed, because I always think C/C++ can do everything

And with enough time, perseverance, and budget you probably can

After all, Excel itself was written (largely) in C and C++, so no reason you can't do the same, in theory.
Whether it is practical is of course another matter entirely.

A quick search of the internet found several libraries that claim to be able to handle XLS documents .
C++ Excel Library to read/write xls/xlsx files - LibXL
C++ Library For Direct Writing Excel Spreadsheets | PRLog
C++ Library for Excel

These are commercial products. The first several pages of search results didn't yield an open source or otherwise free library (except one announcement from 2 years ago stating someone's starting one, but that one died already).