Writing to Disk

I've finally cleaned out all my obvious bugs except this one. When I try to write to a w+ file, the file is overwritten with... nothing. I.e., the file is successfully opened and the string to be written contains printable characters (I checked with printf), but nothing is actually sent to the file.

Here's the function that tries to write, which is also the one I checked the string in.

Code:

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void outline_write(struct outline *this, FILE *file){
    char *text = outline_item_toString(this->root, 0);
    fprintf(file, "%s", text);
    free(text);
}

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Is there any other code that might hold a clue, or am I doing something blatantly wrong in those three lines? Thanks!

Do you have the string enclosed in double quotation marks on both ends of it?

are you closing file before exemining its contents?

Adak, the string is a composite of user input, with indentation and outline numbering added by the program. The program compiles cleanly.

Vart, the program doesn't examine the file; I use gedit to detect the update. (I really should have mentioned that originally.) Is this an inaccurate method?

Quote:

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Originally Posted by Jesdisciple

Vart, the program doesn't examine the file; I use gedit to detect the update. (I really should have mentioned that originally.) Is this an inaccurate method?

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I mean - when you exemined file with editor - has the program already closed the file? OS could delay flushing changes to disk till the file is closed

LOL... As I was thinking about your post, I realized I didn't call fflush. I quit the program and switched back to gedit, and sure enough there are my data.

I wonder what would be necessary to safely allow concurrent editing, other than flushing the stream? I'm in read-write mode, so shouldn't I be able to read the changed file without reopening it?

Thanks so much!

Quote:

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Originally Posted by Jesdisciple

I'm in read-write mode, so shouldn't I be able to read the changed file without reopening it?

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Have you read the manual?
http://www.cplusplus.com/reference/c...dio/fopen.html

Quote:

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For the modes where both read and writing (or appending) are allowed (those which include a "+" sign), the stream should be flushed (fflush) or repositioned (fseek, fsetpos, rewind) between either a reading operation followed by a writing operation or a writing operation followed by a reading operation.

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I have, but I obviously lost some of it (and it's been a while).

Thanks for the help! Now I have to deal with the new flood of read-related bugs, of course... (Side note: I had to change the mode to r+ so there would still be something to read.)