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. When the function failed due to disk full or any error, an `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 */

#### See Also

`f_open, f_putc, f_puts, f_gets, f_close, FIL`

Return