C++ 传递指针给函数

我来给一个简洁版的演示过程:

#include<iostream>
using namespace std;
int get(int *p)
{
    *p = 5;
    return *p;
}
int main()
{
    int a = 1;
    cout<<a<<endl;
    get(&a);
    cout<<a<<endl;
    return 0;
}

传递指针给函数的过程补充

#include <iostream>
#include <ctime>
void getSeconds(unsigned long *par);
int main()
{
    unsigned long sec = 0;
    cout << "Value of sec = :" << sec << endl;
    cout << "Value of &sec = :" << &sec << endl;
    cout << endl;
    getSeconds(&sec);
    // 输出实际值
    cout << "Number of seconds :" << sec << endl;
    return 0;
}
void getSeconds(unsigned long *par)
{
    cout << "Value of *par = :" << *par << endl;
    cout << "Value of par = :" << par << endl;
    cout << "Value of &par = :" << &par << endl;
    cout << endl;
    // 获取当前的秒数
    *par = time(NULL);
    cout << "Value of *par = :" << *par << endl;
    cout << endl;
    return;
}

这是一个求平均数的程序。

#include <iostream>
using namespace std;
 
// 函数声明
double getAverage(int *arr, int size);
 
int main ()
{
   int balance[5] = {1000, 2, 3, 17, 50};  // 带有 5 个元素的整型数组
   double avg;
 
   avg = getAverage( balance, 5 ) ;    // 传递一个指向数组的指针作为参数
 
   cout << "Average value is: " << avg << endl; // 输出返回值
    
   return 0;
}
double getAverage(int *arr, int size)    //再次运用函数，使得sum得以累加
{
  int    i, sum = 0;       
  double avg;          
 
  for (i = 0; i < size; ++i)
  {
    sum += arr[i];
   }
 
  avg = double(sum) / size;    //求平均
 
  return avg;
}