How to: Access an Array Element with a Pointer (C# Programming Guide)
Visual Studio 2012
In an unsafe context, you can access an element in memory by using pointer element access, as shown in the following example:
char* charPointer = stackalloc char[123];
for (int i = 65; i < 123; i++)
{
charPointer[i] = (char)i; //access array elements
}
The expression in square brackets must be implicitly convertible to int, uint, long, or ulong. The operation p[e] is equivalent to *(p+e). Like C and C++, the pointer element access does not check for out-of-bounds errors.
In this example, 123 memory locations are allocated to a character array, charPointer. The array is used to display the lowercase letters and the uppercase letters in two for loops.
Notice that the expression charPointer[i] is equivalent to the expression *(charPointer + i), and you can obtain the same result by using either of the two expressions.
// compile with: /unsafe
class Pointers { unsafe static void Main() { char* charPointer = stackalloc char[123]; for (int i = 65; i < 123; i++) { charPointer[i] = (char)i; } // Print uppercase letters: System.Console.WriteLine("Uppercase letters:"); for (int i = 65; i < 91; i++) { System.Console.Write(charPointer[i]); } System.Console.WriteLine(); // Print lowercase letters: System.Console.WriteLine("Lowercase letters:"); for (int i = 97; i < 123; i++) { System.Console.Write(charPointer[i]); } } }
Uppercase letters: ABCDEFGHIJKLMNOPQRSTUVWXYZ Lowercase letters: abcdefghijklmnopqrstuvwxyz
