Open Source C Library to Read Excel XLS Files

Getting Started with libxls

libxls supports CMake for building and installing the library. Please use the following command.

 mkdir build
cd build

cmake ..
make
 

 git clone https://github.com/libxls/libxls.git
# Or use your preferred protocol instead of https 

Reading Legacy Excel XLS Files via C Library

One of the biggest strengths of libxls is its ability to parse Excel 97–2003 binary XLS files. The library understands the internal structure of these spreadsheets and allows applications to access rows, columns, and cell values without requiring Microsoft Excel. This capability is especially useful for organizations that still archive historical data in XLS format. Developers can easily build import tools and automate data extraction processes while preserving compatibility with older documents. The following example opens an Excel XLS workbook using UTF-8 encoding. Once the workbook is loaded, developers can access worksheets and extract spreadsheet data.

#include 

int main()
{
    xlsWorkBook *workbook;
    workbook = xls_open("sample.xls", "UTF-8");

    if(workbook)
    {
        printf("Workbook opened successfully\n");
        xls_close_WB(workbook);
    }

    return 0;
}

Access Multiple Worksheets via C Library

Many Excel files contain several worksheets that organize information into different sections. libxls provides APIs for navigating and reading each worksheet independently. This feature is useful when processing financial reports, invoices, inventory sheets, or scientific datasets. Developers can loop through all sheets and extract information automatically without user intervention. The following code opens a workbook and retrieves the total number of worksheets available in the file.

#include 

int main()
{
    xlsWorkBook *wb = xls_open("report.xls", "UTF-8");

    if(wb)
    {
        printf("Number of sheets: %d\n", wb->sheets.count);

        xls_close_WB(wb);
    }

    return 0;
}

Reading Cell Values via C Library

The open source libxls allows applications to access individual cells and retrieve their contents. Whether the spreadsheet contains text, numbers, or dates, the library provides straightforward access to cell information. This capability makes libxls suitable for importing spreadsheet data into databases, generating reports, or converting Excel documents into CSV and JSON formats. The following code example reads the first cell in the worksheet and prints its value to the console.

#include 

int main()
{
    xlsWorkBook *wb = xls_open("sample.xls", "UTF-8");

    if(wb)
    {
        xlsWorkSheet *sheet = xls_getWorkSheet(wb, 0);
        xls_parseWorkSheet(sheet);

        xlsCell *cell = xls_cell(sheet, 0, 0);

        if(cell)
            printf("Cell value: %s\n", cell->str);

        xls_close_WS(sheet);
        xls_close_WB(wb);
    }

    return 0;
}

Unicode and Character Encoding Support

Modern applications often work with multilingual spreadsheets. libxls supports Unicode text through configurable character encodings, making it possible to process files containing international languages and special characters. This feature is particularly useful for business applications handling customer names, addresses, and reports in different languages. By specifying UTF-8 encoding, the library correctly interprets Unicode text stored inside Excel files as shown in the following code example.

 
xlsWorkBook *wb = xls_open("employees.xls", "UTF-8");

if(wb)
{
    printf("Workbook loaded using UTF-8 encoding\n");
}