指针（五）————传递指针给函数

#include <iostream> 
using namespace std;
void getSeconds(int *par);
double getAverage(int *arr, int size);//入参是指针，本质上是要求传一个地址过来
 
int main ()
{
   int sec=5;
    cout << "sec :" << sec << endl; 
   getSeconds( &sec );   //传递地址
   cout << "sec is changed by the pointer :" << sec << endl;  // 输出实际值
   // 带有 5 个元素的整型数组
   int balance[5] = {1000, 2, 3, 17, 50};
   double avg;
 
   // 传递一个指向数组的指针作为参数
   avg = getAverage( balance, 5 ) ;//balance是数组，本质上是一个指向数组首元素的地址
 
   // 输出返回值
   cout << "Average value is: " << avg << endl; 
   return 0;
} 
void getSeconds(int *par)
{   
   *par = 100;
   return;
}

double getAverage(int *arr, int size)
{
  int    i, sum = 0;       
  double avg;          
 
  for (i = 0; i < size; ++i)
  {
    sum += arr[i];
   }
 
  avg = double(sum) / size;
 
  return avg;
}

结果

sec :5
sec is changed by the pointer :100
Average value is: 214.4
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