FatFs - f_printf

f_printf

The f_printf function writes formatted string to the file.

int f_printf (
  FIL* fp,          /* [IN] File object */
  const TCHAR* fmt, /* [IN] Format stirng */
  ...
);

Parameters

fp: Pointer to the open file object structure.
fmt: Pointer to the null terminated format string. The terminator charactor will not be written.
...: Optional arguments...

Return Values

When the function succeeded, it returns number of characters written. If the function could not write the generated string to the file due to disk full or an error, EOF (-1) will be returned.

Description

The format control directive is a sub-set of standard library shown as follos:

Type: c C s S d D u U x X b B
Size: l L
Flag: 0 -

QuickInfo

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, '\n's contained in the output are converted to '\r'+'\n'.

When FatFs is configured to Unicode API (_LFN_UNICODE == 1), data types on the srting 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.

Example

    f_printf(&fil, "%d", 1234);            /* "1234" */
    f_printf(&fil, "%6d,%3d%%", -200, 5);  /* "  -200,  5%" */
    f_printf(&fil, "%ld", 12345L);         /* "12345" */
    f_printf(&fil, "%06d", 25);            /* "000025" */
    f_printf(&fil, "%06d", -25);           /* "000-25" */
    f_printf(&fil, "%-6d", 25);            /* "25    " */
    f_printf(&fil, "%u", -1);              /* "65535" or "4294967295" */
    f_printf(&fil, "%04x", 0xAB3);         /* "0ab3" */
    f_printf(&fil, "%08LX", 0x123ABCL);    /* "00123ABC" */
    f_printf(&fil, "%016b", 0x550F);       /* "0101010100001111" */
    f_printf(&fil, "%s", "String");        /* "String" */
    f_printf(&fil, "%8s", "abc");          /* "     abc" */
    f_printf(&fil, "%-8s", "abc");         /* "abc     " */
    f_printf(&fil, "%c", 'a');             /* "a" */
    f_printf(&fil, "%f", 10.0);            /* f_printf lacks floating point support */