unsafe (C# Reference)
The unsafe keyword denotes an unsafe context, which is required for any operation involving pointers. For more information, see Unsafe Code and Pointers (C# Programming Guide).
You can use the unsafe modifier in the declaration of a type or a member. The entire textual extent of the type or member is therefore considered an unsafe context. For example, the following is a method declared with the unsafe modifier:
unsafe static void FastCopy(byte[] src, byte[] dst, int count)
{
// Unsafe context: can use pointers here.
}
The scope of the unsafe context extends from the parameter list to the end of the method, so pointers can also be used in the parameter list:
unsafe static void FastCopy ( byte* ps, byte* pd, int count ) {...}
You can also use an unsafe block to enable the use of an unsafe code inside this block. For example:
unsafe
{
// Unsafe context: can use pointers here.
}
To compile unsafe code, you must specify the /unsafe compiler option. Unsafe code is not verifiable by the common language runtime.
Example
// compile with: /unsafe
class UnsafeTest
{
// Unsafe method: takes pointer to int:
unsafe static void SquarePtrParam(int* p)
{
*p *= *p;
}
unsafe static void Main()
{
int i = 5;
// Unsafe method: uses address-of operator (&):
SquarePtrParam(&i);
Console.WriteLine(i);
}
}
// Output: 25
C# Language Specification
For more information, see the C# Language Specification. The language specification is the definitive source for C# syntax and usage.
See Also
Reference
fixed Statement (C# Reference)
Unsafe Code and Pointers (C# Programming Guide)
Fixed Size Buffers (C# Programming Guide)