From cppreference.com
Defined in header
template<classT>constexprTmidpoint(Ta,Tb)noexcept; (1) (since C++20)template<classT>constexprT*midpoint(T*a,T*b); (2) (since C++20)Computes the midpoint of the integers, floating-points, or pointers a and b.
1) This overload participates in overload resolution only if T is an arithmetic type other than bool.
2) This overload participates in overload resolution only if T is an object type. Use of this overload is ill-formed if T is an
.
Parameters
a, b - integers, floating-points, or pointer values Return value
1) Half the sum of a and b. No overflow occurs. If a and b have integer type and the sum is odd, the result is rounded towards a. If a and b have floating-point type, at most one inexact operation occurs.
2) If a and b point to, respectively, x[i] and x[j] of the same array object x (for the purpose of
), returns a pointer to x[i+(j-i)/2] (or, equivalently x[std::midpoint(i,j)]) where the division rounds towards zero. If a and b do not point to elements of the same array object, the behavior is undefined.
Exceptions
Throws no exceptions.
Notes
Overload (2) can be simply implemented as returna+(b-a)/2; on common platforms. However, such implementation is not guaranteed to be portable, because there may be some platforms where creating an array with number of elements greater than
is possible, and b-a may result in undefined behavior even if both b and a point to elements in the same array.
macroValueStdFeature
(C++20)
, std::midpointExample
Run this code
#include<cstdint>#include<iostream>#include<limits>#include<numeric>intmain(){std::uint32_ta=std::numeric_limits<std::uint32_t>::max();std::uint32_tb=std::numeric_limits<std::uint32_t>::max()-2;std::cout<<"a: "<<a<<'\n'<<"b: "<<b<<'\n'<<"Incorrect (overflow and wrapping): "<<(a+b)/2<<'\n'<<"Correct: "<<std::midpoint(a,b)<<"\n\n";autoon_pointers=[](inti,intj){charconst*text="0123456789";charconst*p=text+i;charconst*q=text+j;std::cout<<"std::midpoint('"<<*p<<"', '"<<*q<<"'): '"<<*std::midpoint(p,q)<<"'\n";};on_pointers(2,4);on_pointers(2,5);on_pointers(5,2);on_pointers(2,6);}Output:
a: 4294967295 b: 4294967293 Incorrect (overflow and wrapping): 2147483646 Correct: 4294967294 std::midpoint('2', '4'): '3' std::midpoint('2', '5'): '3' std::midpoint('5', '2'): '4' std::midpoint('2', '6'): '4' References
C++23 standard (ISO/IEC 14882:2024):
27.10.16 Midpoint [numeric.ops.midpoint]
C++20 standard (ISO/IEC 14882:2020):
25.10.15 Midpoint [numeric.ops.midpoint]
See also
(C++20)
linear interpolation function
(function)