c++ - C++ 2011 中的 nextafter 与 nexttoward 函数？

Question

C++ 2011标准库的nextafter和nexttoward函数有什么区别？

Answer 1

由于函数源自 C，它们不能被重载，这意味着函数有两个不同的名称，但具有不同的参数(-type)。以下是原始签名:

float nextafter(float, float);
float nexttoward(float, long double);

现在标准只是说应该有a few overloads在 C++ 中让事情变得更好(§26.8 [c.math] p11):

Moreover, there shall be additional overloads sufficient to ensure:

1. If any argument corresponding to a double parameter has type long double, then all arguments corresponding to double parameters are effectively cast to long double.
2. Otherwise, if any argument corresponding to a double parameter has type double or an integer type, then all arguments corresponding to double parameters are effectively cast to double.
3. Otherwise, all arguments corresponding to double parameters are effectively cast to float.

See also: ISO C 7.5, 7.10.2, 7.10.6.