值类型 - short int long（带符号的 16 位 32 位 64 位整数）

// assigning a signed short to its minimum value
short s = -32768;

// assigning a signed short to its maximum value
short s = 32767;

// assigning a signed int to its minimum value
int i = -2147483648;

// assigning a signed int to its maximum value
int i = 2147483647;

// assigning a signed long to its minimum value (note the long postfix)
long l = -9223372036854775808L;

// assigning a signed long to its maximum value (note the long postfix)
long l = 9223372036854775807L;

也可以使这些类型可以为空，这意味着除了通常的值之外，还可以分配 null。如果未初始化可空类型的变量，则它将为 null 而不是 0.可以通过在类型后添加问号（？）来标记可空类型。

int a; //This is now 0.
int? b; //This is now null.