1 C++ Write a function that uses the specialization of the template function to get the length of an array.
#include <iostream>
using namespace std;
template <typename Type, size_t N>
inline size_t GetArrayLength(const Type(&)[N])
{
return N;
}
void main()
{
int a []= {,,};
cout << GetArrayLength(a) << endl;
system("pause");
}
2 get/set is automatically generated
Implemented by macro definition
#define ClassVar(permission, type, name, value, funcname) \
public: \
void Set##funcname(type v_val) { name = v_val; } \
type Get##funcname() const { return name; } \
permission: \
type name = value;
Example of use:
ClassVar(private, int, cnt_, 0, Count)
generation
public:
void SetCount(int v_val) { cnt_ = v_val; }
int GetCount() const { return cnt_; }
private:
int cnt_ = 0;
3 inline keyword
inline int max(int a, int b)
return a > b ? a : b
}
int main()
{
int a, b, c;
cin >> a >> b >> c;
cout << max(a, b) << endl;
return 0;
}
4 Release the storage space of the vector
The source code of reverse, you can see that when reserve(0), there is no logic to release excess space
template
void
vector<_Tp, _Allocator>::reserve(size_type __n)
{
if (__n > capacity())
{
allocator_type& __a = this->__alloc();
__split_buffer __v(__n, size(), __a);
__swap_out_circular_buffer(__v);
}
}
5 Iteration of the macro itself
#define BOOST_PP_COMMA_IF(cond) BOOST_PP_IF(cond, BOOST_PP_COMMA, BOOST_PP_EMPTY)()
#define BOOST_PP_IF(cond, t, f) BOOST_PP_IIF(BOOST_PP_BOOL(cond), t, f)
#define BOOST_PP_IIF(bit, t, f) BOOST_PP_IIF_I(bit, t, f)
#define BOOST_PP_IIF_I(bit, t, f) BOOST_PP_IIF_ ## bit(t, f)
# define BOOST_PP_IIF_0(t, f) f
# define BOOST_PP_IIF_1(t, f) t
#define BOOST_PP_BOOL(x) BOOST_PP_BOOL_I(x)
# define BOOST_PP_BOOL_I(x) BOOST_PP_BOOL_ ## x
# define BOOST_PP_BOOL_0 0
# define BOOST_PP_BOOL_1 1
# define BOOST_PP_BOOL_2 1
... ...
# define BOOST_PP_BOOL_256 1