How to create sequential files on an SD card

[FPicc.1]

HI everyone, I'm working on creating a sequence of files, that everytime the program starts to run, it creates a sequential file of the last one created. But I'm having troubles trying to create a logic that compares the name of the last file and create a sequence of it, and also I want to put constant data at it, so can i put the f_puts function at the main only, or I need to put it in the while?

Also, to create a .csv file, It's just name it that way?

I'm using a NUCLEO stm32WL

Thanks in advance!