Double

An xsd:double is an IEEE-754 64-bit floating point number, written in scientific notation.

Canonical form has no leading “+” sign, at most 1 leading or trailing zero such that there is at least 1 digit on either side of the decimal point, and always has an exponent, like “12.34E56”, “-1.0E-2”, and “-0.0E0”. The special values negative infinity, positive infinity, and not-a-number are written “-INF”, “INF”, and “NaN”, respectively.

Non-canonical form allows a leading “+”, any number of leading and trailing zeros, any number of digits (including zero) on either side of the point, and does not require an exponent or decimal point, like “+1E3”, “1E+3”, “.5E3”, “4.2”, and “42”.

ExessResult exess_read_double(double *out, const char *str)

Read an xsd:double string after any leading whitespace.

Values beyond the range of double will produce -INF or INF.

Parameters

  • out – Set to the parsed value, or NAN on error.

  • str – String input.

Returns

The count of characters read, and a status code.

ExessResult exess_write_double(double value, size_t buf_size, char *buf)

Write a canonical xsd:double string.

Any double value is supported. Reading the resulting string with exess_read_double() will produce exactly value, except the extra bits in NaNs are not preserved.

Parameters

  • value – Value to write.

  • buf_size – The size of buf in bytes.

  • buf – Output buffer, or null to only measure.

Returns

The count of characters in the output and status ExessStatus.EXESS_SUCCESS, or ExessStatus.EXESS_NO_SPACE if the buffer is too small.

EXESS_MAX_DOUBLE_LENGTH

The maximum length of a canonical xsd:double string, 24.