c++ - Structure tag and name, why does a local variable declared as name compile? -

in code saw there structure defined this:

typedef struct tagmystruct {     int numberone;     int numbertwo; } mystruct;

the way understand this, tagmystruct new data type , mystruct variable created right there.

at place, used this:

mystruct *pstruct = new mystruct;

and compiled fine visual studio 2010. how valid c++? thought mystruct variable , not type?

no. tagmystruct name of struct. in c, unlike c++, must explicitly use struct keyword every time use struct type. example

tagmystruct x; //error struct tagmystruct x; //ok

to avoid writing struct time, struct tagmystruct typedef'd mystruct. can write

mystruct x; //ok, same struct tagmystruct x;

what thought (a variable definition) without typedef keyword, this

struct tagmystruct {     int numberone;     int numbertwo; } mystruct;

btw

mystruct pstruct = new mystruct; //error cannot convert mystruct* mystruct

is not valid c or c++ anyway. maybe mean

mystruct* pstruct = new mystruct; //valid c++ (invalid c - use malloc instead of new in c)

hth

shell