static unsafe void ArrayAndString_Test()
{
int[] arr = { 1, 2, 3, 4, 5 };
string s = "test";
//无法获取托管类型(P)的地址和大小，或声明指向它的指针
//&arr;
//&arr[0];
//&s;
fixed(int *p = &arr[0])
{
Print.Address((long)p);
}
fixed(int *p = arr)
{
Print.Address((long)p);
}
fixed(char *p = s)
{
Print.Address((long)p);
}
}
static unsafe void Main(string[] args)
{
//Console.WriteLine(nameof(StackOverflow_Test));
//StackOverflow_Test();
unsafe
{
int *a = stackalloc int[10];
Print.Address((long)a);
}
Span <int> aa = stackalloc int[10];
unsafe
{
fixed(int *p = aa)
{
Print.Address((long)p);
}
}
Console.WriteLine();
Span_Test();
Console.WriteLine();
Console.WriteLine(nameof(StructAlloc_Test));
StructAlloc_Test();
}
static unsafe void StructAlloc_Test()
{
var n = sizeof(A <int>);
Console.WriteLine(n);
Span <A <int> > arr = stackalloc A <int>[]
{
new A <int>()
{
X = 1, Y = 1
},
new A <int>()
{
X = 2, Y = 2
},
new A <int>()
{
X = 3, Y = 3
}
};
fixed(A <int> *p = arr)
{
var p1 = p + 1;
Print.Address((long)p);
Print.Address((long)p1);
Console.WriteLine(p1->X);
}
}
static unsafe void Main(string[] args)
{
var obj = new P();
//无法获取托管类型(P)的地址和大小，或声明指向它的指针
//fixed (int* p = &obj)
//{
//}
fixed(int *p = &obj.x)
{
*p = 1;
//p++; //p是只读的，不能修改
int *p2 = p;
p2++;
*p2 = 10;//y=10
Print.Address((long)p);
}
fixed(PP *p = &obj.pp)
{
p->x = 1;
p->y = 2;
(*p).x = 1;
(*p).y = 2;
Print.Address((long)p);
}
fixed(int *xp = &obj.pp.x, yp = &obj.pp.y)
{
Print.Address((long)xp);
Print.Address((long)yp);
}
Console.WriteLine(obj.x);
Console.WriteLine(obj.y);
Console.WriteLine();
Console.WriteLine(nameof(ArrayAndString_Test));
ArrayAndString_Test();
Console.WriteLine();
Console.WriteLine(nameof(Span_Test));
Span_Test();
Console.WriteLine();
Console.WriteLine(nameof(FixedSizeBuffers_Test));
FixedSizeBuffers_Test();
}
static unsafe void StackOverflow_Test()
{
const int len = 1024;//1k
//run on my computer, the max stack size 1494k, more than will throw StackOverflowException
const int max = 1494;
while (i < max)
{
i++;
var a = stackalloc byte[len];
Console.WriteLine(i);
Print.Address((long)a);
}
}
static unsafe void Index_Test()
{
Index i1 = 0; // number 3 from beginning
Index i2 = ^ 4; // number 4 from end
int[] a = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
fixed(int *p = a, pp = &a[i1])
{
Print.Address((long)p);
Print.Address((long)pp);
}
Console.WriteLine($"{a[i1]}, {a[i2]}"); // "3, 6"
}
static unsafe void FixedSizeBuffers_Test()
{
var a1 = new SB()
{
arr = new int[5]
};
var a2 = new FSB();
Print.Address((long)&a2);
Print.Address((long)a2.arr);
Print.Address((long)&a2.arr);//数组指针变量的地址
Print.Address((long)&a2.x);
//Console.WriteLine(sizeof(SB));//SB作为托管类型不能计算大小
Console.WriteLine(sizeof(FSB));
}
static unsafe void Span_Test()
{
var a = stackalloc byte[8];
Print.Address((long)a);
Print.Address((long)(a + 4));
Span <int> span = new Span <int>(a, 2);
span[0] = 1;
span[1] = 2;
fixed(int *p = span)
{
Print.Address((long)p);
var pp = p;
Print.Address((long)(pp + 1));
Print.Address((long)(pp + 2));
}
}
static void ManagedHeap_Test()
{
var arr = new int[10] {
1, 2, 3, 4, 5, 6, 7, 8, 9, 0
};
var span = new Span <int>(arr);
foreach (var s in span)
{
Console.WriteLine(s);
}
unsafe
{
fixed(int *p = arr, pp = span)
{
Print.Address((long)p);
Print.Address((long)pp);
}
}
}
static unsafe void Range_Test()
{
Range r = new Range(Index.Start, Index.End);//等价于 0..^0
int[] a = { 0, 1, 2, 3 };
var aa = a[r];
Span <int> s = a[r];
a[0] = 10;
fixed(int *p = a, pp = aa, ps = s)
{
Print.Address((long)p);
Print.Address((long)pp);
Print.Address((long)ps);
}
foreach (var i in aa)
{
Console.WriteLine(i);
}
}
static void Stack_Test()
{
Span <int> span = stackalloc int[5];
//span[5] = 10;//throw System.IndexOutOfRangeException
unsafe
{
//stack 由高地址向低地址分配空间
var i = stackalloc int[1];
var arr = stackalloc int[4];
var span2 = new Span <int>((void *)arr, sizeof(int) * 5);
fixed(int *p = span2, p5 = &span2[4])
{
Print.Address((long)arr);
Print.Address((long)i);
Print.Address((long)p);
Print.Address((long)p5);
}
}
}
