C ++ pointers vs array

C ++ pointers

Pointers and arrays are closely related. In fact, pointers and arrays in many cases are interchangeable. For example, a pointer to the beginning of the array, the array can be accessed by using pointer arithmetic or array index. Consider the following program:

#include <iostream>
 
using namespace std;
const int MAX = 3;
 
int main ()
{
   int  var[MAX] = {10, 100, 200};
   int  *ptr;
 
   // 指针中的数组地址
   ptr = var;
   for (int i = 0; i < MAX; i++)
   {
      cout << "Address of var[" << i << "] = ";
      cout << ptr << endl;
 
      cout << "Value of var[" << i << "] = ";
      cout << *ptr << endl;
 
      // 移动到下一个位置
      ptr++;
   }
   return 0;
}

When the above code is compiled and executed, it produces the following results:

Address of var[0] = 0xbfa088b0
Value of var[0] = 10
Address of var[1] = 0xbfa088b4
Value of var[1] = 100
Address of var[2] = 0xbfa088b8
Value of var[2] = 200

However, pointers and arrays are not completely interchangeable. For example, consider the following program:

#include <iostream>
 
using namespace std;
const int MAX = 3;
 
int main ()
{
   int  var[MAX] = {10, 100, 200};
 
   for (int i = 0; i < MAX; i++)
   {
      *var = i;    // 这是正确的语法
      var++;       // 这是不正确的
   }
   return 0;
}

Pointer operator * is applied to the var is perfectly acceptable, but the modification var value is illegal. This is because var is a pointer to the beginning of the array constant, it can not serve as the left value.

Because an array name corresponds to a pointer constant, they do not change the value of the array, you can still use the pointer form of expression. For example, the following is a valid statement, the var [2] 500 assignment:

*(var + 2) = 500;

The above statement is valid, and can successfully compile, because var unchanged.

C ++ pointers