指针与数组

c/c++ 大多数情况下对待这两个的方式一样，导致区别变得模糊。
但是如果循环处理时，还是有性能的区别：
The first program uses the expression (array[index] != 0). This requires the compiler to generate an index operation, which takes longer than a simple pointer de-reference: ((*array_ptr) != 0). The expression at the end of this program, array_ptr - array, computes how far array_ptr is into the array.

int array[10] = {4, 5, 8, 9, 8, 1, 0, 1, 9, 3};
int *array_ptr;
main()
{
array_ptr = array;
while ((*array_ptr) != 0)   //指针循环
    ++array_ptr;
index = 0;
while (array[index] != 0)   //数组循环
    ++index;
cout << "Number of elements before zero <<
(array_ptr - array) << '\n';
return (0);
}

类型描述

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编译器总结

看到这个链接，编译器还有好多产品
https://www.openmp.org/resources/openmp-compilers-tools/

列表：ARM/AMD/Intel/富士通/HPE/IBM/Apple/NVIDIA/Oracle, 都有自己的编译器。clang/Flang/gcc/

语法总结

goto

结构初始化

designated initializer），是一个ISO标准
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++ 和后++

The prefix form ++variable is preferred over the suffix form variable ++ because it allows the compiler to generate slightly simpler code.
会产生side effect的操作符。

packed

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virtual

The virtual keyword identifies a member function that can be overridden by a member
function in the derived class. If we are using a derived class, then C++ will look for members
in the derived class and then in the base class, in that order. If we are using a base class
variable (even if the actual instance is a derived class), then C++ will search only the base
class for the member function. The exception is when the base class defines a virtual
function. In this case, the derived class is searched and then the base class.
The “= 0” tells C++ that these member functions are pure virtual functions. That is, they can
never be called directly. Any class containing one or more pure virtual functions is called an
abstract class.