Hi all,
I'm trying to solve a problem of writting multiple variables to a single file. Normally I'd use fwrite to write a single variable, however I'd like to write multiple variables to a single file, for example int x,y,z, double a,b, struct m,n. Is there a wayto do this?

The reason I'm doing this is I'm moving from using NVRAM (mmapped) on an ARM board to uing a board with no NVRAM and a harddrive so I need to store about 30 variables that are normally written to NVRAM. I'm an embeedded programmer so my knowledge of file functions is limited.

Thanks.

So 'fprintf' is out of the question, or did I misunderstood your question ? (I have no knowledge about embedded programming in detail, so my answer might be quite naive).

Hi Thanks,
What I was looking for was writing one variable at a time rather than a stream, but I supose I could do a new line for each variable then when I read new line to each varaible line number and read the value from there?

So your question is about how to get back the value of variables you wrote in? (My first reaction to your question was "call fwrite() again...")

You have remember which offset you wrote to, then you can use fseek to move the stream there and fread to get the variable. Or read in the same order you write.

If your data is fixed length and not too big, I would suggest packing everything in one struct. Harddrives usually can't read/write less than 512 bytes at a time (although maybe your embedded system is different, I think flash drives can read in smaller chunks).

As a matter of fact this question is simple so I am afraid I don't get it correctly.

Would it be possible to use
where fp is a pointer to a file you opened with fopen.
You can also write multiple fprintf values one by one, up to you whether or not you terminate with a newline.

To get those values back you could use exactly the inverse of fprintf, fscanf. Since you wrote the values yourself you know exactly the amount and the format, hence it is a fairly safe operation.

jlinkels

Use 'sprintf' to any string and then 'fprintf'.
Or directly,instead 'fprintf', use 'write'