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 */

#### See Also

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

Return