Reading SD card from the end versus beginning

Projects Programming
1

The reference for the SD library states to use the SD.open("filename", FILE_WRITE); when trying to read your SD card data back from the end of the file vice FILE_READ which starts from the beginning. I'm building a datalogger that writes to the file in the following format:

mm/dd/yy , hhmm , temp

It works great if I use FILE_READ, but will not read out the card at all if I use FILE_WRITE to open the file for a read operation

Also......since I would want it printed as above would I need to create them as strings so that the last string would be read out vice it just reading each piece of data from back to front creating a "backwards" printout. right now I just "filename.print" everything.

From the SD library reference page.........

Syntax
SD.open(filepath)
SD.open(filepath, mode)

Parameters
filename: the name the file to open, which can include directories (delimited by forward slashes, /) - char *

mode (optional): the mode in which to open the file, defaults to FILE_READ - byte. one of:

FILE_READ: open the file for reading, starting at the beginning of the file.
FILE_WRITE: open the file for reading and writing, starting at the end of the file.

Returns

2

The reference for the SD library states to use the SD.open("filename", FILE_WRITE); when trying to read your SD card data back from the end of the file vice FILE_READ which starts from the beginning.

No, it does not say this.

FILE_READ: open the file for reading, starting at the beginning of the file.
FILE_WRITE: open the file for reading and writing, starting at the end of the file.

The FILE_WRITE attribute opens the file in such a way the writing occurs at the end of the file. The location for read is a different story. Reading from the end of file would make no sense. Reading always advances the read pointer, so if the read pointer is at the end of the file, and you read, all you get is the end of file flag being set.