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Add to_chars floating point docs

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Matt Borland
2023-05-01 15:56:36 +02:00
parent fb2b4034da
commit 900c650258
1 changed files with 43 additions and 4 deletions
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47
doc/charconv/to_chars.adoc
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@@ -24,6 +24,9 @@ BOOST_CHARCONV_CONSTEXPR to_chars_result(char* first, char* last, Integral value
template <typename Integral>
BOOST_CHARCONV_CONSTEXPR to_chars_result<bool>(char* first, char* last, Integral value, int base) noexcept = delete;
template <typename Real>
to_chars_result(char* first, char* last, Real value, boost::charconv::chars_format fmt = boost::charconv::chars_format::general, int precision) noexcept;
----
== to_chars_result
@@ -38,17 +41,27 @@ BOOST_CHARCONV_CONSTEXPR to_chars_result<bool>(char* first, char* last, Integral
== to_chars
* first, last - pointers to the character buffer
* value - the value to be paresed into the buffer
* base - the integer base to use. Must be between 2 and 36 inclusive
* from_chars for integral type is constexpr (BOOST_CHARCONV_CONSTEXPR is defined) when compiled using `-std=c++14` or newer and a compiler with `__builtin_ is_constant_evaluated`
* base (integer only) - the integer base to use. Must be between 2 and 36 inclusive
* fmt (float only) - the floating point format
* precision (float only) - the number of decimal places required
== to_chars for integral types
=== to_chars for integral types
* All built-in integral types are allowed except bool which is deleted
* These functions have been tested to support `__int128` and `unsigned __int128` when compiling with `-std=gnu++11` or newer
* from_chars for integral type is constexpr (BOOST_CHARCONV_CONSTEXPR is defined) when compiled using `-std=c++14` or newer and a compiler with `__builtin_ is_constant_evaluated`
* These functions have been tested to support `__int128` and `unsigned __int128`
=== to_chars for floating point types
* The following will be returned when handling different values of `NaN`
** +qNaN returns "nan"
** -qNaN returns "-nan(ind)"
** +sNaN returns "nan(snan)"
** -sNaN returns "-nan(snan)"
== Examples
=== Basic Usage
[source, c++]
==== Integral
----
char buffer[64] {};
int v = 42;
@@ -56,9 +69,18 @@ to_chars_result r = boost::charconv::to_chars(buffer, buffer + sizeof(buffer) -
assert(r.ec == 0);
assert(!strcmp(buffer, "42")); // strcmp returns 0 on match
----
==== Floating Point
----
char buffer[64] {};
double v = 1e300;
to_chars_result r = boost::charconv::to_chars(buffer, buffer + sizeof(buffer) - 1, v);
assert(r.ex == 0);
assert(!strcmp(buffer, "1e+300"));
----
=== Hexadecimal
[source, c++]
==== Integral
----
char buffer[64] {};
int v = 42;
@@ -66,13 +88,30 @@ to_chars_result r = boost::charconv::to_chars(buffer, buffer + sizeof(buffer) -
assert(r.ec == 0);
assert(!strcmp(buffer, "2a")); // strcmp returns 0 on match
----
==== Floating Point
----
char buffer[64] {};
double v = -1.08260383390082946e+307;
to_chars_result r = boost::charconv::to_chars(buffer, buffer + sizeof(buffer) - 1, v, boost::charconv::chars_format::hex);
assert(r.ex == 0);
assert(!strcmp(buffer, "-1.ed5658af91a0fp+1019"));
----
=== ERANGE
[source, c++]
==== Integral
----
char buffer[3] {};
int v = -1234;
to_chars_result r = boost::charconv::to_chars(buffer, buffer + sizeof(buffer) - 1, v, 16);
assert(r.ec == ERANGE);
----
==== Floating Point
----
char buffer[3] {};
double v = 1.2345;
auto r = boost::charconv::to_chars(buffer, buffer + sizeof(buffer) - 1, v);
assert(r.ec == ERANGE);
----
In the event of ERANGE to_chars_result.ptr is first