Using Arrays (C++)

 

The latest version of this topic can be found at Using Arrays (C++).

You can access individual elements of an array by using the array subscript operator ([ ]). If a one-dimensional array is used in an expression that has no subscript, the array name evaluates to a pointer to the first element in the array.

// using_arrays.cpp  
int main() {  
   char chArray[10];  
   char *pch = chArray;   // Evaluates to a pointer to the first element.  
   char   ch = chArray[0];   // Evaluates to the value of the first element.  
   ch = chArray[3];   // Evaluates to the value of the fourth element.  
}  

When you use multidimensional arrays, you can use various combinations in expressions.

// using_arrays_2.cpp  
// compile with: /EHsc /W1  
#include <iostream>  
using namespace std;  
int main() {  
   double multi[4][4][3];   // Declare the array.  
   double (*p2multi)[3];  
   double (*p1multi);  
  
   cout << multi[3][2][2] << "\n";   // C4700 Use three subscripts.  
   p2multi = multi[3];               // Make p2multi point to  
                                     // fourth "plane" of multi.  
   p1multi = multi[3][2];            // Make p1multi point to  
                                     // fourth plane, third row  
                                     // of multi.  
}  

In the preceding code, multi is a three-dimensional array of type double. The p2multi pointer points to an array of type double of size three. In this example, the array is used with one, two, and three subscripts. Although it is more common to specify all subscripts, as in the cout statement, it is sometimes useful to select a specific subset of array elements, as shown in the statements that follow cout.

See Also

Arrays