The f_putc funciton puts a character to the file.
int f_putc ( TCHAR chr, /* [IN] A character to put */ FIL* fp /* [IN] File object */ );
When the character was written successfuly, it returns number of characters written. When the function failed due to disk full or any error, an EOF (-1) will be returned.
When FatFs is configured to Unicode API (_LFN_UNICODE == 1), character encoding on the string fuctions, f_putc, f_puts, f_printf and f_gets function, is also switched to Unicode. The character encoding on the file to be read/written via those functions is selected by _STRF_ENCODE option.
This is a wrapper function of f_write function. Available when _FS_READONLY == 0 and _USE_STRFUNC is 1 or 2. When it is set to 2, a '\n' is converted to '\r'+'\n'.