ptrdiff_t (long integer or __int64, depending on the target platform)
在CRTDEFS.H头文件中定义
该类型的变量用作保存两个指针作减法运算的结果
Result of subtraction of two pointers.
楼主应该多查查msdn
注明:以上回答来自joyzml
This is the type returned by the subtraction operation between two pointers. This is a signed integral type, and as such can be casted to compatible fundamental data types.