What is the difference between `new` and `new()` for a struct in C/C++? [duplicate]

This question already has answers here: Closed 12 years ago.

Possible Duplicate:

Do the parentheses after the type name make a difference with new?

In some code, I recently saw a struct like this:

typedef struct MyStruct {
    int numberOne;
    int numberTwo;
} MYSTRUCT;

Later, I tried instantiating one of these structs using

MyStruct *pStruct = new MyStruct();

which worked fine with Visual Studio 2010, but failed with an obscure linker error on a different compiler. It took a 开发者_如何学Cwhile until we found out that omitting the braces like this

MyStruct *pStruct = new MyStruct;

solved the issue.

So, what exactly is the difference between these two invocations and which one is the right one to use?

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new MyStruct performs default initialization, which in your case does nothing.

new MyStruct() performs value initialization, which in your case sets both int variables to zero.