Important Notice

The pages on this site contain documentation for very old MS-DOS software, purely for historical purposes. If you're looking for up-to-date documentation, particularly for programming, you should not rely on the information found here, as it will be woefully out of date.

 ◄Summary► ◄Example►                         ◄Up► ◄Contents► ◄Index► ◄Back►
────────────────────────────────────────────────────────────────────────────
 
     The atof, atoi, atol, and _atold functions convert a character
     string to a double-precision floating-point value (atof), an
     integer value (atoi), a long integer value (atol), or a long
     double value (_atold). The input string is a sequence of
     characters that can be interpreted as a numeric value of the
     specified type.
 
     The size of <string> that can be handled by the atof or _atold
     function is limited to 100 characters.
 
     The function stops reading the input string at the first character
     that it cannot recognize as part of a number. This character may
     be the null character (\0) terminating the string.
 
     The atof and _atold functions expect <string> to have the
     following form:
 
          [whitespace][{sign}][digits][.digits][{d|D|e|E}[sign]digits]
 
     A <whitespace> consists of space and/or tab characters, which are
     ignored; <sign> is either + or -; and <digits> contains one or
     more decimal digits. If no digits appear before the decimal point,
     at least one must appear after the decimal point. The decimal
     digits may be followed by an exponent, which consists of an
     introductory letter (d, D, e, or E) and an optionally signed
     decimal integer.
 
     The atoi and atol functions do not recognize decimal points or
     exponents. The <string> argument for these functions has the form
 
          [whitespace] [sign] digits
 
     where <whitespace>, <sign>, and <digits> are exactly as described
     above for atof.
 
     Return Value
 
     Each function returns the double, int, long, or long double value
     produced by interpreting the input characters as a number. The
     return value is 0 (for atoi), 0L (for atol) and 0.0 (for atof and
     _atold) if the input cannot be converted to a value of that type.
     The return value is undefined in case of overflow.
                                    -♦-