String Conversions
beman::big_int provides to_string and to_wstring, which return a freshly
allocated std::string or std::wstring holding the textual representation of
a basic_big_int. They are the arbitrary-precision analogues of the standard
std::to_string and std::to_wstring, and are implemented on top of
to_chars: the conversion is
locale-independent, accepts any base from 2 to 36, and is usable in a
constant expression. When you need to write into an existing buffer, or to
avoid allocating at all, use to_chars directly.
Synopsis
namespace beman::big_int {
template <std::size_t b, class A>
constexpr std::string to_string(const basic_big_int<b, A>& value, int base = 10);
template <std::size_t b, class A>
constexpr std::wstring to_wstring(const basic_big_int<b, A>& value, int base = 10);
} // namespace beman::big_intThe output matches what to_chars would
write: the magnitude is rendered with no leading zeros, except that a value of
zero is rendered as the single character 0, and a negative value is prefixed
with a single -. Digit values below ten use the characters 0-9; digit
values of ten or more use the lowercase letters a-z. No prefix (such as
0x) is written.
to_string
template <std::size_t b, class A>
constexpr std::string to_string(const basic_big_int<b, A>& value, int base = 10);Returns a std::string holding value rendered in the given base.
-
Preconditions:
2 <= base <= 36. -
Returns: A
std::stringcontaining the textual representation ofvalue, as if written byto_chars. -
Throws: Any exception thrown while allocating the result string (for example,
std::bad_alloc); the conversion itself does not throw. -
Remarks: The function is usable in a constant expression. The result is sized from the bit width of
valueup front, so the digits are produced in a single pass with at most one allocation.
to_wstring
template <std::size_t b, class A>
constexpr std::wstring to_wstring(const basic_big_int<b, A>& value, int base = 10);Behaves exactly like to_string, but returns a std::wstring. The digit
characters and the minus sign all belong to the basic execution character set,
so each character has the same value in the wide result as in the narrow one.
-
Preconditions:
2 <= base <= 36. -
Returns: A
std::wstringcontaining the same characters asto_string(value, base), each widened towchar_t. -
Throws: Any exception thrown while allocating the result string (for example,
std::bad_alloc); the conversion itself does not throw. -
Remarks: The function is usable in a constant expression.