how to change , into .

dynamitron · Joined: 18 Mar 2009 Posts: 38

I have a code which write a string to a SD card. The file on the SD card has the extension .csv to be easily readable by excel
Before to write I use "sprintf" to convert numerical data into char.

My question : I want that the conversion of the temperature [0] from float to string generates a "," in place of a "." for the decimal separator.

how is it possible to do that ?
Thanks for the answers

temtronic · Posted: Tue May 08, 2012 3:21 pm

If I understand it right..
you want to convert 1.234 to 1,234

Easy enough to do a simple if comma then replace with period function but...

The problem I see is that when you import into say Excel as a dotCSV file, Excel will split the temperature reading 1,234 into two ( 1 and 234).

Is this what you really want ?

Perhaps an example or two would be helpful.

dynamitron · Joined: 18 Mar 2009 Posts: 38

For example the value of the float is 21.21
If I use the above code, after the sprintf, I find 21.21 in the result but I would like to have 21,21

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

He wants European notation for the decimal point.

temtronic · Posted: Tue May 08, 2012 5:44 pm

Yeah, but that'll get messed up when imported as a Comma Separated Variable file unless he can use a different separater than a comma.
I don't use Excel to often though I am real familiar with Visicalc.

jeremiah · Joined: 20 Jul 2010 Posts: 1349

I thought that if you encase it in quotes that it retains the comma? It's been a while with csv format files.

asmboy · Joined: 20 Nov 2007 Posts: 2128 Location: albany ny

actually its EZ

LET the float be formatted with the decimal point

excel has the OPTION after importing the .CSV data
to change the representation format

inside the spreadsheet is the place to do it......

Mike Walne · Joined: 19 Feb 2004 Posts: 1785 Location: Boston Spa UK

OK. So let Excel do the donkey work.

If he really HAS to convert to using a comma there's no problem importing into Excel, since there's an option to change the separator to semicolon, tab and/or any other character.

Mike

Ttelmah · Joined: 11 Mar 2010 Posts: 19520

Yes. This is very much related to the problem another user was having a while back, where 123,45 inside a command, was returning '45'. In C itself, the decimal separator _must_ be '.'.

The key is to read up on CSV. In CSV files, there are two possible legal 'cell' separators. The ',', and the ';'. (Many programs allow others, but these are the defined ones) In the CSV definitions, _if_ your country locale uses ',' as the decimal separator, then you are meant to use ';' as the cell separator. Using double inverted commas round the numbers (effectively outputting then as strings), sometimes works, but can also give problems with some applications. Quite a few programs take the 'CSV is a separate standard' approach, and whatever the local decimal separator, use '.' inside the CSV file, and convert to the local standard when this is read. Personally this seems to give less problems...
So, if you want to be compatible with other programs, the 'safest' approach seems to be to always use . as the decimal separator.
Alternatively, use ',', and switch to using ';' as the cell separator. In the code you post, you are using ':' as the separator, and quite a few programs won't support this.

If you must output using the comma, then use sprintf, to put the number into a text string, and then use:

dynamitron · Joined: 18 Mar 2009 Posts: 38

Thank you all, I will use your answers to find the easiest solution for me.