For questions related to C++20's compiler-generated comparisons, either implicitly generated from hand-written operator<=>, or explicitly requested with = default.
Questions tagged [default-comparisons]
4 questions
4
votes
3 answers
c++20 default comparison operator and empty base class
c++20 default comparison operator is a very convenient feature. But I find it less useful if the class has an empty base class.
The default operator<=> performs lexicographical comparison by
successively comparing the base (left-to-right…
wanghan02
- 1,227
- 7
- 14
3
votes
0 answers
Three-Way comparison operator(<=>) not defined for std::string
I am attempting to make use of c++20's new Three-Way operator(<=>) capabilities in my programs, but it appears that this operator is not defined for strings, as this program
#include
#include
using namespace std;
int main()
{
…
InterdimensionalCat
- 41
- 1
- 3
3
votes
1 answer
Why C++20 allows defaulted comparison to compile even when it is deleted?
Consider the following code:
struct A {
};
struct B {
A a;
bool operator == (const B& other) const = default;
};
clang gives a nice warning :
warning: explicitly defaulted equality comparison operator is
implicitly deleted…
NoSenseEtAl
- 28,205
- 28
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- 277
2
votes
1 answer
Equivalent of std::less for default comparsons operator (<=>)
Does c++20 defines something similar to std::less for default comparsons operator (<=>).
I would like define some datasructure with customizable comparator as map or unordered_map do.
template ,
struct…
Dewfy
- 23,277
- 13
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- 121