C++使用技巧(十二):函数返回一个数组

#include<iostream>

using namespace std;

//函数声明
int * fun1();
int * fun2();
int * fun3(int * const buf); //buf 实际上是个传出参数，const表示buf的指向不能更改
void dispArr(int *arr ,int n);

const int arrlen = 10;

int main()
{
    //方法一,返回局部变量的首地址
    int * arr;
    arr = fun1();
    cout << "这是方法一" << endl;

    //dispArr(arr, arrlen); //运行会报错

    /*方法二，在函数内部通过new动态创建数组，
     然后记得在main函数使用完数组后将其delete下*/
    cout << "这是方法二" << endl;
    int *arr1;
    arr1 = fun2();
    dispArr(arr1, arrlen);
    delete arr1;

    //方法三，由调用者自己申请缓存区和释放缓存区
    cout << "这是方法三" << endl;
    int *arr2 = new int[arrlen];
    int *ret = fun3(arr2);
    dispArr(arr2, arrlen);
    delete arr2;

    return 0;
}

//函数定义

int *fun1()
{
    int temp[arrlen];
    for (int i = 0; i < arrlen;++i)
    {
        temp[i] = i;
    }
    return temp;
}

int *fun2()
{
    int *temp = new int[arrlen];
    for (int i = 0; i < arrlen; i++)
    {
        temp[i] = i;
    }
    return temp;
}
int *fun3(int* const buf)
{
   if(buf==NULL)
   {
        cerr<<"error: null ptr @buf"<<endl;
        return NULL;
   }
   for(int i=0; i<arrlen; i++)
   {
        buf[i]=i;
   }
   return buf;
}

void dispArr(int* arr, int n)
{
    for (int i = 0; i < n; i++)
    {
        cout << "arr" << "[" << i << "]" << " is:" <<arr[i]<<endl;
    }
}

参考：https://www.cnblogs.com/walter-xh/p/6192800.html?ivk_sa=1024320u
https://www.runoob.com/cplusplus/cpp-return-arrays-from-function.html