C++练习：返回值指针or引用

#include <cstddef> using std::size_t; #include <iostream> using std::cout; using std::endl; // code to illustrate declarations of array-related types int arr[10]; // arr is an array of ten ints int *p1[10]; // p1 is an array of ten pointers int (*p2)[10] = &arr; // p2 points to an array of ten ints typedef int arrT[10]; // arrT is a synonym for the type array of ten ints // two ways to declare function returning pointer to array of ten ints arrT* func(int i); // use a type alias int (*func(int i))[10]; // direct declaration // two arrays int odd[] = {1,3,5,7,9}; int even[] = {0,2,4,6,8}; // function that returns a pointer to an int in one of these arrays int *elemPtr(int i) { // returns a pointer to the first element in one of these arrays return (i % 2) ? odd : even; } // returns a pointer to an array of five int elements //返回一个指针，该指针指向5个int元素构成的数组 int(*arrPtr(int i))[5] { return (i % 2) ? &odd : &even; // returns a pointer to the array } // returns a reference to an array of five int elements //返回一个由5个int元素构成的数组的引用 int (&arrRef(int i))[5] { return (i % 2) ? odd : even; } int main() { int *p = elemPtr(6); // p points to an int int (*arrP)[5] = arrPtr(5); // arrP points to an array of five ints int (&arrR)[5] = arrRef(4); // arrR refers to an array of five ints for (size_t i = 0; i < 5; ++i) // p points to an element in an array, which we subscript cout << p[i] << endl; for (size_t i = 0; i < 5; ++i) // arrP points to an array, // we must dereference the pointer to get the array itself cout << (*arrP)[i] << endl; for (size_t i = 0; i < 5; ++i) // arrR refers to an array, which we can subscript cout << arrR[i] << endl; return 0; }