How to: Access an Array Element with a Pointer (C# Programming Guide)
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.
Example
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
See Also
Reference
Pointer Expressions (C# Programming Guide)
Pointer types (C# Programming Guide)
fixed Statement (C# Reference)