值型別 - ushort uint ulong（無符號 16 位 32 位 64 位整數）

// assigning an unsigned short to its minimum value
ushort s = 0;

// assigning an unsigned short to its maximum value
ushort s = 65535;

// assigning an unsigned int to its minimum value
uint i = 0;

// assigning an unsigned int to its maximum value
uint i = 4294967295;

// assigning an unsigned long to its minimum value (note the unsigned long postfix)
ulong l = 0UL;

// assigning an unsigned long to its maximum value (note the unsigned long postfix)
ulong l = 18446744073709551615UL;

也可以使這些型別可以為空，這意味著除了通常的值之外，還可以分配 null。如果未初始化可空型別的變數，則它將為 null 而不是 0.可以通過在型別後新增問號（？）來標記可空型別。

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