unsafe static void Main()
{
Test test = new Test();
Test *p = &test;
p->x = 9; //(*p).x=9;
System.Console.WriteLine(test.x);
}
unsafe static void Main(string[] args)
{
Test x = new Test();
Test *p = &x;
//p->n = 20;
(*p).n = 20;
Console.WriteLine(x.n);
Console.ReadKey();
}
unsafe static void Main(string[] args)
{
int len = Marshal.SizeOf(typeof(Test));
IntPtr mem = Marshal.AllocCoTaskMem(len);
Test * ptr = (Test *)mem;
ptr->member1 = 42;
// call method
//..
int value = ptr->member1;
Marshal.FreeCoTaskMem(mem);
}
private static Test Foo(Test *t)
{
// This read was too wide.
return(*t);
}
static void Main(string[] args)
{
/*the fixed statement tells
* the garbage collector to “pin” the object and not move it around. This may have an
* impact on the efficiency of the runtime, so fixed blocks should be used only briefly,
* and heap allocation should be avoided within the fixed block.*/
Program pgm = new Program();
unsafe
{
fixed(int *p = &pgm.x) //Pins pgm
{
*p = 9;
}
Console.WriteLine(pgm.x);
}
/*& The address-of operator returns a pointer to the address of a variable
* The dereference operator returns the variable at the address of a pointer
* -> The pointer-to-member operator is a syntactic shortcut,
* in which x->y is equivalent to (*x).y */
unsafe
{
Test test = new Test();
Test *p = &test;
p->x = 9;
Console.WriteLine(test.x);
}
//Arrays: The stackalloc keyword
//Memory can be allocated in a block on the stack explicitly using the stackalloc
//keyword.Since it is allocated on the stack, its lifetime is limited to the
//execution of the method
unsafe
{
int *a1 = stackalloc int[10];
for (int i = 0; i < 10; ++i)
{
Console.WriteLine(a1[i]); // Print raw memory
}
}
//Fixed-size buffers
//THe fixed keyword has another use which is to create fixed-size
//buffers within structs
Console.WriteLine(new UnsafeClass("Christian Troy"));
//Void*
/*A void pointer (void*) makes no assumptions about the type of the underlying data
* and is useful for functions that deal with raw memory. An implicit conversion exists
* from any pointer type to void*. A void* cannot be dereferenced, and arithmetic
* operations cannot be performed*/
short[] a = { 1, 1, 2, 3, 5, 8, 13, 21, 34, 55 };
unsafe
{
fixed(short *p = a)
{
//sizeof returns size of value-type in bytes
Zap(p, a.Length * sizeof(short));
}
}
foreach (short x in a)
{
System.Console.WriteLine(x); // Prints all zeros
}
Console.ReadLine();
}
