Converts its argument to a null-terminated string of ASCII digits
    and returns the address of the string. The string is stored in a
    thread-specific memory location created by the Compaq C RTL.

    Format

      #include  <stdlib.h>

      char *ecvt  (double value, int ndigits, int *decpt, int *sign);

1 - Arguments

 value

    An object of type double that is converted to a null-terminated
    string of ASCII digits.

 ndigits

    The number of ASCII digits to be used in the converted string.

 decpt

    The position of the decimal point relative to the first character
    in the returned string. A negative int value means that the
    decimal point is decpt number of spaces to the left of the
    returned digits (the spaces being filled with zeros). A 0 value
    means that the decimal point is immediately to the left of the
    first digit in the returned string.

 sign

    An integer value that indicates whether the value argument is
    positive or negative. If value is negative, the function places
    a nonzero value at the address specified by sign. Otherwise, the
    function assigns 0 to the address specified by sign.

2 - Description

    The ecvt function converts value to a null-terminated string
    of length ndigits, and returns a pointer to it. The resulting
    low-order digit is rounded to the correct digit for outputting
    ndigits digits in C E-format. The decpt argument is assigned the
    position of the decimal point relative to the first character in
    the string.

    Repeated calls to the ecvt function overwrite any existing
    string.

    The ecvt, fcvt, and gcvt functions represent the following
    special values specified in the IEEE Standard for floating-point
    arithmetic:

    Value         Representation

    Quiet NaN     NaNQ
    Signalling    NaNS
    NaN
    +Infinity     Infinity
    -Infinity     -Infinity

    The sign associated with each of these values is stored into the
    sign argument. In IEEE floating-point representation, a value
    of 0 (zero) can be positive or negative, as set by the sign
    argument.

    See also gcvt and fcvt.

3 - Return Value

    x                  The value of the converted string.