unbox

• The object reference is popped from the stack and unboxed to a value type pointer
  从堆栈中弹出对象引用并取消装箱为值类型指针。
• Box instruction converts the raw unboxed value type into an object reference type
  指令将“原始” （未装箱）值类型转换成对象引用（
• When unboxing , the casting process can take four times as long as an assignment
  取消装箱时，强制转换过程所需时间可达赋值操作的四倍。
• To a lesser degree , the cast required for unboxing is also expensive computationally
  次之，取消装箱所需的强制转换也需要进行大量的计算。
• The debugger expression evaluator does not support boxing and unboxing in visual c
  调试器表达式运算符不支持visual c + +中的装箱和取消装箱。
• Use generic collections to avoid the boxing and unboxing overhead for value types
  使用泛型集合以避免值类型的装箱和取消装箱产生的系统开销。
• Operator only considers reference conversions , boxing conversions , and unboxing conversions
  运算符只考虑引用转换、装箱转换和取消装箱转换。
• Converts the boxed representation of a type specified in the instruction to its unboxed form
  将指令中指定类型的已装箱的表示形式转换成未装箱形式。
• And , therefore , boxing and unboxing typically occur if storing or retrieving a value type
  类型，所以在存储或检索值类型时通常发生装箱和取消装箱操作。
• The object reference is popped from the stack and unboxed to the type specified in the instruction
  从堆栈中弹出对象引用，取消装箱到指令中指定的类型。