cxlsx_to_csv

cxlsx_to_csv is a simple converter of XLSX Excel 2007 files (a.k.a. Open Office XML) to CSV

FEATURES:

• Simple converter, pretty fast as done in C.
• Only depends on miniz (included for convenience) and one XML library, that can be either Expat or Parsifal or Mini-XML.

The XLSX format is just a glorified ZIP (that I open thanks to miniz), containing a set of XML files (that I parse thanks to Expat or Mini-XML or Parsifal). Notice that Excel stores dates as the number of days that have elapsed since 1-January-1900 (the Excel Epoch), and this program exports dates simply as the floating point value they are stored.

SYNOPSIS:

cxlsx_to_csv -if input.xlsx [-sh sheet_id] [-of output.csv]
    input.xlsx  input spreadsheet in Excel 2007 format (Office Open XML)
    sheet_id    number of the sheet within the workbook (default is first one)
    output.csv  output CSV file (default is STDOUT)

COMPILATION:

It is possible to choose at compilation time from a number of XML parsing libraries:

• Expat
  cc -DCONFIG_EXPAT -o cxlsx_to_csv cxlsx_to_csv.c -l expat
• Parsifal
  cc -DCONFIG_PARSIFAL -o cxlsx_to_csv cxlsx_to_csv.c -lparsifal
• Mini-XML
  cc -DCONFIG_MXML -o cxlsx_to_csv cxlsx_to_csv.c -l mxml

If you choose no XML library, then you may benchmark the time used exclusively by the decompressing step:
cc -o cxlsx_to_csv cxlsx_to_csv.c

SPEED COMPARISON:

• Tested under Ubuntu 15.10 on an Intel i3-3217U CPU @ 1.80GHz, with a Crucial CT120M500 SSD.
• Locale set to LC_ALL=C.UTF-8
• The input spreadsheet a.xlsx has 48665 rows and 46 columns, and weights 9165KB.

Tool	Command	Time (real/user/sys)
cxlsx_to_csv (Decompressing time)	cxlsx_to_csv -if a.xlsx -of a.csv	1.574s/1.564s/0.008s
cxlsx_to_csv (Expat)	cxlsx_to_csv -if a.xlsx -of a.csv	3.020s/2.960s/0.064s
cxlsx_to_csv (Parsifal)	cxlsx_to_csv -if a.xlsx -of a.csv	3.957s/3.884s/0.072s
cxlsx_to_csv (Mini-XML)	cxlsx_to_csv -if a.xlsx -of a.csv	4.967s/4.880s/0.088s
Gnumeric	ssconvert --export-type=Gnumeric_stf:stf_assistant -O 'eol=windows separator=, format=raw transliterate-mode=escape quoting-mode=auto' a.xlsx a.csv	11.869s/11.692s/0.184s
LibreOffice 5	soffice --headless --convert-to csv a.xlsx	12.779s/15.292s/0.536s
xlsx2csv	xlsx2csv.py a.xlsx a.csv	39.925s/39.684s/0.148s