libxls - Read XLS files from C

This is libxls, a C library for reading Excel files in the nasty old binary OLE format, plus a command-line tool for converting XLS to CSV (named, appropriately enough, xls2csv).

After several years of neglect, libxls is under new management as of the 1.5.x series. Head over to releases to get the latest stable version of libxls 1.5, which fixes many security vulnerabilities found in libxls 1.4 and earlier.

Libxls 1.5 also includes new APIs for parsing files stored in memory buffers, and returns errors instead of exiting upon encountering malformed input. If you find a bug, please file it on the GitHub issue tracker.

Changes to libxls since 1.4:

Hosted on GitHub (hooray!)
New in-memory parsing API (see xls_open_buffer)
Internals rewritten to return errors instead of exiting
Heavily fuzz-tested with clang’s libFuzzer, fixing many memory leaks and CVEs
Improved compatibility with C++
Continuous integration tests on Mac, Linux, and Windows
Lots of other small fixes, see the commit history

The C API is pretty simple, this will get you started:

xls_error_t error = LIBXLS_OK;
xlsWorkBook *wb = xls_open_file("/path/to/finances.xls", "UTF-8", &error);
if (wb == NULL) {
    printf("Error reading file: %s\n", xls_getError(error));
    exit(1);
}
for (int i=0; i<wb->sheets.count; i++) { // sheets
    xlsWorkSheet *work_sheet = xls_getWorkSheet(work_book, i);
    error = xls_parseWorkSheet(work_sheet);
    for (int j=0; j<=work_sheet->rows.lastrow; j++) { // rows
        xlsRow *row = xls_row(work_sheet, j);
        for (int k=0; k<=work_sheet->rows.lastcol; k++) { // columns
            xlsCell *cell = &row->cells.cell[k];
            // do something with cell
            if (cell->id == XLS_RECORD_BLANK) {
                // do something with a blank cell
            } else if (cell->id == XLS_RECORD_NUMBER) {
               // use cell->d, a double-precision number
            } else if (cell->id == XLS_RECORD_FORMULA) {
                if (strcmp(cell->str, "bool") == 0) {
                    // its boolean, and test cell->d > 0.0 for true
                } else if (strcmp(cell->str, "error") == 0) {
                    // formula is in error
                } else {
                    // cell->str is valid as the result of a string formula.
                }
            } else if (cell->str != NULL) {
                // cell->str contains a string value
            }
        }
    }
    xls_close_WS(work_sheet);
}
xls_close_WB(wb);

The library also includes a CLI tool for converting Excel files to CSV:

./xls2csv /path/to/file.xls

The man page for xls2csv has more details.

Libxls should run fine on both little-endian and big-endian systems, but if not please open an issue.

If you want to hack on the source, you should first familiarize yourself with the Microsoft Excel File Format as well as Compound Document file format (documentation provided by the nice folks at OpenOffice.org).

Installation

If you want a stable version, check out the Releases section, which has copies of everything you’ll find in Sourceforge, and download version 1.5.0 or later.

For full instructions see INSTALL, or here’s the tl;dr:

To install a stable release:

./configure
make
make install

If you’ve cloned the git repository, you’ll need to run this first:

./autogen.sh

That will generate all the supporting files. It assumes autotools is already installed on the system (and also expects Autoconf Archive to be present).

Language bindings

If C is not your cup of tea, you can make use of libxls in several other languages, including: