C++ - Concept example
C++20 introduced concept. The following code shows the example of using concept.
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#include <concepts>
#include <iostream>
#include <vector>
// Define a concept that expects a .size() member function
template<typename T>
concept HasSize = requires(T a) {
{ a.size() } -> std::convertible_to<std::size_t>;
};
// Use the concept to constrain a function
void print_size(const HasSize auto& container) {
std::cout << "Size is: " << container.size() << '\n';
}
int main() {
std::vector<int> vec = {1, 2, 3, 4, 5};
print_size(vec); // OK! vector has size()
std::string str = "hello";
print_size(str); // OK! string also has size()
// int x = 5;
// print_size(x); // Compile-time error! int doesn't have size()
}