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Synopsis:
    #include <stdio.h>
    int printf( const char *format, ... );

Description:
    The printf function writes output to the file designated by  stdout
    under control of the argument format.  The format string is described
    below.

Returns:
    The printf function returns the number of characters written, or a
    negative value if an output error occurred.  When an error has occurred,
     errno contains a value indicating the type of error that has been
    detected.

See Also:
    _bprintf, cprintf, fprintf, sprintf, _vbprintf, vcprintf, vfprintf,
    vprintf, vsprintf

Example:
    #include <stdio.h>

    void main()
      {
        char *weekday, *month;

        weekday = "Saturday";
        month = "April";
        printf( "%s, %s %d, %d\n",
              weekday, month, 18, 1987 );
        printf( "f1 = %8.4f f2 = %10.2E x = %#08x i = %d\n",
                23.45,      3141.5926,   0x1db,     -1 );
      }

    produces the following:

    Saturday, April 18, 1987
    f1 =  23.4500 f2 =  3.14E+003 x = 0x0001db i = -1

Format Control String:
    The format control string consists of ordinary characters, that are
    written exactly as they occur in the format string, and conversion
    specifiers, that cause argument values to be written as they are
    encountered during the processing of the format string.  An ordinary
    character in the format string is any character, other than a percent
    character (%), that is not part of a conversion specifier.  A conversion
    specifier is a sequence of characters in the format string that begins
    with a percent character (%) and is followed, in sequence, by the
    following:

     *  zero or more format control flags that can modify the final effect
        of the format directive
     *  an optional decimal integer, or an asterisk character ('*'), that
        specifies a minimum field width to be reserved for the formatted
        item
     *  an optional precision specification in the form of a period
        character (.), followed by an optional decimal integer or an
        asterisk character (*)
     *  an optional type length specification:  one of "h", "l", "L", "w",
        "N" or "F"
     *  a character that specifies the type of conversion to be performed:
         one of the characters "cdeEfFgGinopsuxX".

    The valid format control flags are:

    "-"
        the formatted item is left-justified within the field; normally,
        items are right-justified

    "+"
        a signed, positive object will always start with a plus character
        (+); normally, only negative items begin with a sign

    " "
        a signed, positive object will always start with a space character;
        if both "+" and " " are specified, "+" overrides " "

    "#"
        an alternate conversion form is used:

         *  for "o" (unsigned octal) conversions, the precision is
            incremented, if necessary, so that the first digit is "0".
         *  for "x" or "X" (unsigned hexadecimal) conversions, a non-zero
            value is prepended with "0x" or "0X" respectively
         *  for "e", "E", "f", "g" or "G" (any floating-point) conversions,
            the result always contains a decimal-point character, even if no
            digits follow it; normally, a decimal-point character appears in
            the result only if there is a digit to follow it
         *  in addition to the preceding, for "g" or "G" conversions,
            trailing zeros are not removed from the result


    If no field width is specified, or if the value that is given is less
    than the number of characters in the converted value (subject to any
    precision value), a field of sufficient width to contain the converted
    value is used.  If the converted value has fewer characters than are
    specified by the field width, the value is padded on the left (or right,
    subject to the left-justification flag) with spaces or zero characters
    ("0").  If the field width begins with a zero, the value is padded with
    zeros, otherwise the value is padded with spaces.  If the field width is
    "*", a value of type int from the argument list is used (before a
    precision argument or a conversion argument) as the minimum field width.
     A negative field width value is interpreted as a left-justification
    flag, followed by a positive field width.

    As with the field width specifier, a precision specifier of "*" causes a
    value of type int from the argument list to be used as the precision
    specifier.  If no precision value is given, a precision of 0 is used.
     The precision value affects the following conversions:

     *  for "d", "i", "o", "u", "x" and "X" (integer) conversions, the
        precision specifies the minimum number of digits to appear
     *  for "e", "E" and "f" (fixed-precision, floating-point) conversions,
        the precision specifies the number of digits to appear after the
        decimal-point character
     *  for "g" and "G" (variable-precision, floating-point) conversions,
        the precision specifies the maximum number of significant digits to
        appear
     *  for "s" (string) conversions, the precision specifies the maximum
        number of characters to appear

    A type length specifier affects the conversion as follows:

     *  "h" causes a "d", "i", "o", "u", "x" or "X" (integer) format
        conversion to treat the argument as a short int or unsigned short
        int argument.  Note that, although the argument may have been
        promoted to an int as part of the function call, the value is
        converted to the smaller type before it is formatted.
     *  "h" causes an "f" format conversion to interpret a long argument as
        a fixed-point number.  The value is formatted with the same rules as
        for floating-point values.  This is a WATCOM extension.
     *  "h" causes an "n" (converted length assignment) operation to assign
        the converted length to an object of type unsigned short int
     *  "h" causes an "s" operation to treat the input string as an ASCII
        character string composed of 8-bit characters.
     *  "l" causes a "d", "i", "o", "u", "x" or "X" (integer) conversion to
        process a long int or unsigned long int argument;
     *  "l" causes an "n" (converted length assignment) operation to assign
        the converted length to an object of type unsigned long int
     *  "l" or "w" cause an "s" operation to treat the input string as a
        wide character string (a string composed of characters of type
         wchar_t) or a 16-bit Unicode character string.
     *  "F" causes the pointer associated with "n", "p", "s" conversions to
        be treated as a far pointer;
     *  "L" causes an "e", "E", "f", "g", "G" (double) conversion to process
        a long double argument;
     *  "N" causes the pointer associated with "n", "p", "s" conversions to
        be treated as a near pointer;

    The valid conversion type specifiers are:

    c
        An argument of type int is converted to a value of type char and the
        corresponding ASCII character code is written to the output stream.

    d, i
        An argument of type int is converted to a signed decimal notation
        and written to the output stream.  The default precision is 1, but
        if more digits are required, leading zeros are added.

    e, E
        An argument of type double is converted to a decimal notation in the
        form [-]d.ddde[+|-]ddd similar to FORTRAN exponential (E) notation.
         The leading sign appears (subject to the format control flags) only
        if the argument is negative.  If the argument is non-zero, the digit
        before the decimal-point character is non-zero.  The precision is
        used as the number of digits following the decimal-point character.
         If the precision is not specified, a default precision of six is
        used.  If the precision is 0, the decimal-point character is
        suppressed.  The value is rounded to the appropriate number of
        digits.  For "E" conversions, the exponent begins with the character
        "E" rather than "e".  The exponent sign and a three-digit number
        (that indicates the power of ten by which the decimal fraction is
        multiplied) are always produced.

    f
        An argument of type double is converted to a decimal notation in the
        form [-]ddd.ddd similar to FORTRAN fixed-point (F) notation.  The
        leading sign appears (subject to the format control flags) only if
        the argument is negative.  The precision is used as the number of
        digits following the decimal-point character.  If the precision is
        not specified, a default precision of six is used.  If the precision
        is 0, the decimal-point character is suppressed, otherwise, at least
        one digit is produced before the decimal-point character.  The value
        is rounded to the appropriate number of digits.

    g, G
        An argument of type double is converted using either the "f" or "e"
        (or "E", for a "G" conversion) style of conversion depending on the
        value of the argument.  In either case, the precision specifies the
        number of significant digits that are contained in the result.  "e"
        style conversion is used only if the exponent from such a conversion
        would be less than -4 or greater than the precision.  Trailing zeros
        are removed from the result and a decimal-point character only
        appears if it is followed by a digit.

    n
        The number of characters that have been written to the output stream
        is assigned to the integer pointed to by the argument.  No output is
        produced.

    o
        An argument of type int is converted to an unsigned octal notation
        and written to the output stream.  The default precision is 1, but
        if more digits are required, leading zeros are added.

    p, P
        An argument of type void * is converted to a value of type int and
        the value is formatted as for a hexadecimal ("x") conversion.

    s
        Characters from the string specified by an argument of type char *,
        up to, but not including the terminating null character ('\0'), are
        written to the output stream.  If a precision is specified, no more
        than that many characters are written.

    hs
        Characters from the string specified by an argument of type char *,
        up to, but not including the terminating null character ('\0'), are
        written to the output stream.  If a precision is specified, no more
        than that many characters are written (e.g., %.7ls).

    ls, ws
        Characters from the string specified by an argument of type wchar_t
        *, up to, but not including the terminating null character (L'\0'),
        are written to the output stream.  If a precision is specified, no
        more than that many characters are written (e.g., %.7ls).

    u
        An argument of type int is converted to an unsigned decimal notation
        and written to the output stream.  The default precision is 1, but
        if more digits are required, leading zeros are added.

    x, X
        An argument of type int is converted to an unsigned hexadecimal
        notation and written to the output stream.  The default precision is
        1, but if more digits are required, leading zeros are added.
         Hexadecimal notation uses the digits "0" through "9" and the
        characters "a" through "f" or "A" through "F" for "x" or "X"
        conversions respectively, as the hexadecimal digits.  Subject to the
        alternate-form control flag, "0x" or "0X" is prepended to the
        output.

    Any other conversion type specifier character, including another percent
    character (%), is written to the output stream with no special
    interpretation.

    The arguments must correspond with the conversion type specifiers, left
    to right in the string; otherwise, indeterminate results will occur.

    If the value corresponding to a floating-point specifier is infinity, or
    not a number (NAN), then the output will be "inf" or "-inf" for
    infinity, and "nan" or "-nan" for NAN's.

    For example, a specifier of the form "%8.*f" will define a field to be
    at least 8 characters wide, and will get the next argument for the
    precision to be used in the conversion.

Classification:
    ANSI, (except for F and N modifiers)

Systems:
    All