An introduction to the C++ programming language for game engine development.

2. ‫معرفی‬Utility‫ها‬
‫بندی‬ ‫جمع‬

3.  Clock, duration
 Function type, iterator_traits, is_arithmetic, …
 Pair, tuple

4. 01. using namespace std::chrono; // see §35.2
02. auto t0 = high_resolution_clock::now();
03. do_work();
04. auto t1 = high_resolution_clock::now();
05. cout << duration_cast<milliseconds>(t1–t0).count() << "msecn";

5. 01. // smallest positive float (§40.2)
02. constexpr float min = numeric_limits<float>::min();
03.
04. // the number of bytes in an int
05. constexpr int szi = sizeof(int);

6. 01. // for random-access iterators we can subscript into [beg:end)
02. template<typename Ran>
03. void sort_helper(Ran beg, Ran end, random_access_iterator_tag)
04. {
05. sort(beg,end); // just sort it
06. }
01. // for forward iterators we can traverse [beg:end)
02. template<typename For>
03. void sort_helper(For beg, For end, forward_iterator_tag)
04. {
05. // initialize a vector from [beg:end)
06. vector<decltype(*beg)> v {beg,end};
07. sort(v.begin(),v.end());
08. // copy the elements back
09. copy(v.begin(),v.end(),beg);
10. }

7. 01. template<typname C>
02. void sort(C& c)
03. {
04. using Iter = Iterator_type<C>;
05. sort_helper(c.begin(),c.end(),Iterator_category<Iter>{});
06. }

8. 01. // yes, int is an arithmetic type
02. bool b1 = Is_arithmetic<int>();
03.
04. // no, std::string is not an arithmetic type
05. bool b2 = Is_arithmetic<string>();
01. template<typename Scalar>
02. class complex {
03. Scalar re, im;
04. public:
05. static_assert(Is_arithmetic<Scalar>()
06. , "Sorry, I only support complex of arithmetic types");
07. // ...
08. };

9. 01. void f(vector<string>& v)
02. {
03. // pp is a pair<vector<string>::iterator,int>
04. auto pp = make_pair(v.begin(),2);
05. // ...
06. }
01. // the type is explicitly specified
02. tuple<string,int,double> t2("Sild",123, 3.14);
03.
04. // the type is deduced t is a tuple<string,int,double>
05. auto t = make_tuple(string("Herring"),10, 1.23);
06.
07. string s = get<0>(t); // get first element of tuple
08. int x = get<1>(t);
09. double d = get<2>(t);