2021-09-22 17:23:25 +00:00
|
|
|
= Constexpr =
|
|
|
|
|
|
|
|
|
|
Constexpr is this great C++11 feature that marks a value or function to be
|
|
|
|
|
known/executed at compile time. This is great for things likes config.hpp
|
|
|
|
|
files, compile time string hashes, and more.
|
|
|
|
|
|
|
|
|
|
== Example ==
|
|
|
|
|
|
|
|
|
|
{{{C++
|
|
|
|
|
unsigned int constexpr const_hash(char const *str){
|
2022-02-01 02:07:42 +00:00
|
|
|
return *input ?
|
2021-09-22 17:23:25 +00:00
|
|
|
static_cast<unsigned_int>(*input) + 33 * const_hash(input + 1) :
|
|
|
|
|
5381;
|
|
|
|
|
}
|
2022-02-01 02:07:42 +00:00
|
|
|
|
2021-09-22 17:23:25 +00:00
|
|
|
void main(){
|
|
|
|
|
constexpr char* const_str = "12345";
|
|
|
|
|
switch(const_hash(const_str)){
|
|
|
|
|
case const_hash("12345"):
|
|
|
|
|
std::cout << "Found 12345\n";
|
|
|
|
|
break;
|
|
|
|
|
case const_hash("54321"):
|
|
|
|
|
std::cout << "Found 54321\n";
|
|
|
|
|
break;
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
}}}
|
|
|
|
|
|
|
|
|
|
Switch statements can only accept integers in C/C++, however using this we can
|
|
|
|
|
convert compile time strings into integers. This is wonderful for making code
|
|
|
|
|
more readable, without relying to much on C macros, which are not type aware.
|
|
|
|
|
|
|
|
|
|
[[C++]]
|
