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. When the function failed due to disk full or any error, an EOF (-1) will be returned.

Description

The f_printf() is a wrapper function of f_write(). The format control directive is a sub-set of standard library shown as follos:

QuickInfo

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(), 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 */

See Also

f_open, f_putc, f_puts, f_gets, f_close, FIL

Return