Aminet 18/aminetcdnumber181997.iso/Aminet/misc/emu/AROSdev.lha/AROS/compiler/clib/printf.c

C/C++ Source or Header | 1997-01-28 | 10.6 KB | 287 lines

/*
    (C) 1995-96 AROS - The Amiga Replacement OS
    $Id: printf.c,v 1.7 1997/01/28 17:03:00 digulla Exp $

    Desc: ANSI C function printf()
    Lang: english
*/

/*****************************************************************************

    NAME */
#include <stdio.h>
#include <stdarg.h>

    int printf (

/*  SYNOPSIS */
    const char * format,
    ...)

/*  FUNCTION
    Formats a list of arguments and prints them to standard out.

    The format string is composed of zero or more directives: ordinary
    characters (not %), which are copied unchanged to the output
    stream; and conversion specifications, each of which results in
    fetching zero or more subsequent arguments Each conversion
    specification is introduced by the character %. The arguments must
    correspond properly (after type promotion) with the conversion
    specifier. After the %, the following appear in sequence:

    \begin{itemize}
    \item Zero or more of the following flags:

    \begin{description}
    \item{#} specifying that the value should be converted to an
    ``alternate form''. For c, d, i, n, p, s, and u conversions, this
    option has no effect. For o conversions, the precision of the
    number is increased to force the first character of the output
    string to a zero (except if a zero value is printed with an
    explicit precision of zero). For x and X conversions, a non-zero
    result has the string `0x' (or `0X' for X conversions) prepended to
    it. For e, E, f, g, and G conversions, the result will always
    contain a decimal point, even if no digits follow it (normally, a
    decimal point appears in the results of those conversions only if a
    digit follows). For g and G conversions, trailing zeros are not
    removed from the result as they would otherwise be.

    \item{0} specifying zero padding. For all conversions except n, the
    converted value is padded on the left with zeros rather than
    blanks. If a precision is given with a numeric conversion (d, i, o,
    u, i, x, and X), the 0 flag is ignored.

    \item{-} (a negative field width flag) indicates the converted
    value is to be left adjusted on the field boundary. Except for n
    conversions, the converted value is padded on the right with
    blanks, rather than on the left with blanks or zeros. A -
    overrides a 0 if both are given.

    \item{ } (a space) specifying that a blank should be left before a
    positive number produced by a signed conversion (d, e, E, f, g, G,
    or i). + specifying that a sign always be placed before a number
    produced by a signed conversion. A + overrides a space if both are
    used.

    \item{'} specifying that in a numerical argument the output is to
    be grouped if the locale information indicates any. Note that many
    versions of gcc cannot parse this option and will issue a warning.

    \end{description}

    \item An optional decimal digit string specifying a minimum field
    width. If the converted value has fewer characters than the field
    width, it will be padded with spaces on the left (or right, if the
    left-adjustment flag has been given) to fill out the field width.

    \item An optional precision, in the form of a period (`.') followed
    by an optional digit string. If the digit string is omitted, the
    precision is taken as zero. This gives the minimum number of digits
    to appear for d, i, o, u, x, and X conversions, the number of
    digits to appear after the decimal-point for e, E, and f
    conversions, the maximum number of significant digits for g and G
    conversions, or the maximum number of characters to be printed from
    a string for s conversions.

    \item The optional character h, specifying that a following d, i,
    o, u, x, or X conversion corresponds to a short int or unsigned
    short int argument, or that a following n conversion corresponds to
    a pointer to a short int argument.

    \item The optional character l (ell) specifying that a following d,
    i, o, u, x, or X conversion applies to a pointer to a long int or
    unsigned long int argument, or that a following n conversion
    corresponds to a pointer to a long int argument. Linux provides a
    non ANSI compliant use of two l flags as a synonym to q or L. Thus
    ll can be used in combination with float conversions. This usage
    is, however, strongly discouraged.

    \item The character L specifying that a following e, E,
    f, g, or G conversion corresponds to a long double
    argument, or a following d, i, o, u, x, or X conversion corresponds to a long long argument. Note
    that long long is not specified in ANSI C and
    therefore not portable to all architectures.

    \item The optional character q. This is equivalent to L. See the
    STANDARDS and BUGS sections for comments on the use of ll, L, and
    q.

    \item A Z character specifying that the following integer (d, i, o,
    u, i, x, and X), conversion corresponds to a size_t argument.

    \item A character that specifies the type of conversion to be
    applied.

    A field width or precision, or both, may be indicated by an
    asterisk `*' instead of a digit string. In this case, an int
    argument supplies the field width or precision. A negative field
    width is treated as a left adjustment flag followed by a positive
    field width; a negative precision is treated as though it were
    missing.

    The conversion specifiers and their meanings are:

    \begin{description}
    \item{diouxX} The int (or appropriate variant) argument is
    converted to signed decimal (d and i), unsigned octal (o, unsigned
    decimal (u, or unsigned hexadecimal (x and X) notation. The letters
    abcdef are used for x conversions; the letters ABCDEF are used for
    X conversions. The precision, if any, gives the minimum number of
    digits that must appear; if the converted value requires fewer
    digits, it is padded on the left with zeros.

    \item{eE} The double argument is rounded and converted in the style
    [<->]d.dddedd where there is one digit before the decimal-point
    character and the number of digits after it is equal to the
    precision; if the precision is missing, it is taken as 6; if the
    precision is zero, no decimal-point character appears. An E
    conversion uses the letter E (rather than e) to introduce the
    exponent. The exponent always contains at least two digits; if the
    value is zero, the exponent is 00.

    \item{f} The double argument is rounded and converted to decimal
    notation in the style [-]ddd.ddd, where the number of digits after
    the decimal-point character is equal to the precision
    specification. If the precision is missing, it is taken as 6; if
    the precision is explicitly zero, no decimal-point character
    appears. If a decimal point appears, at least one digit appears
    before it.

    \item{g} The double argument is converted in style f or e (or E for
    G conversions). The precision specifies the number of significant
    digits. If the precision is missing, 6 digits are given; if the
    precision is zero, it is treated as 1. Style e is used if the
    exponent from its conversion is less than -4 or greater than or
    equal to the precision. Trailing zeros are removed from the
    fractional part of the result; a decimal point appears only if it
    is followed by at least one digit.

    \item{c} The int argument is converted to an unsigned char, and the
    resulting character is written.

    \item{s} The ``char *'' argument is expected to be a pointer to an
    array of character type (pointer to a string). Characters from the
    array are written up to (but not including) a terminating NUL
    character; if a precision is specified, no more than the number
    specified are written. If a precision is given, no null character
    need be present; if the precision is not specified, or is greater
    than the size of the array, the array must contain a terminating
    NUL character.

    \item{p} The ``void *'' pointer argument is printed in hexadecimal
    (as if by %#x or %#lx).

    \item{n} The number of characters written so far is stored into the
    integer indicated by the ``int *'' (or variant) pointer argument.
    No argument is converted.

    \item{%} A `%' is written. No argument is converted. The complete
    conversion specification is `%%'.

    \end{description}
    \end{itemize}

    In no case does a non-existent or small field width cause
    truncation of a field; if the result of a conversion is wider than
    the field width, the field is expanded to contain the conversion
    result.

    INPUTS
    format - Format string as described above
    ... - Arguments for the format string

    RESULT
    The number of characters written to stdout or EOF on error.

    NOTES

    EXAMPLE
    To print a date and time in the form `Sunday, July 3,
    10:02', where weekday and month are pointers to strings:

        #include <stdio.h>

        fprintf (stdout, "%s, %s %d, %.2d:%.2d\n",
            weekday, month, day, hour, min);

    To print to five decimal places:

        #include <math.h>
        #include <stdio.h>

        fprintf (stdout, "pi = %.5f\n", 4 * atan(1.0));

    To allocate a 128 byte string and print into it:

        #include <stdio.h>
        #include <stdlib.h>
        #include <stdarg.h>

        char *newfmt(const char *fmt, ...)
        {
        char *p;
        va_list ap;

        if ((p = malloc(128)) == NULL)
            return (NULL);

        va_start(ap, fmt);

        (void) vsnprintf(p, 128, fmt, ap);

        va_end(ap);

        return (p);
        }

    BUGS
    All functions are fully ANSI C3.159-1989 conformant, but provide
    the additional flags q, Z and ' as well as an additional behaviour
    of the L and l flags. The latter may be considered to be a bug, as
    it changes the behaviour of flags defined in ANSI C3.159-1989.

    The effect of padding the %p format with zeros (either by the 0
    flag or by specifying a precision), and the benign effect (i.e.,
    none) of the # flag on %n and %p conversions, as well as
    nonsensical combinations such as are not standard; such
    combinations should be avoided.

    Some combinations of flags defined by ANSI C are not making sense
    in ANSI C (e.g. %Ld). While they may have a well-defined behaviour
    on Linux, this need not to be so on other architectures. Therefore
    it usually is better to use flags that are not defined by ANSI C at
    all, i.e. use q instead of L in combination with diouxX conversions
    or ll. The usage of q is not the same as on BSD 4.4, as it may be
    used in float conversions equivalently to L.

    Because sprintf and vsprintf assume an infinitely long string,
    callers must be careful not to overflow the actual space; this is
    often impossible to assure.

    SEE ALSO
    fprintf(), vprintf(), vfprintf(), sprintf(), vsprintf(),
    vnsprintf()

    INTERNALS

    HISTORY
    15.10.1996 digulla created
    11.12.1996 digulla added manual after printf(3C) man page

******************************************************************************/
{
    int     retval;
    va_list args;

    va_start (args, format);

    retval = vfprintf (stdout, format, args);

    va_end (args);

    fflush (stdout);

    return retval;
} /* printf */