g++ compile error. help

[pfsi]

main.cpp
1: typedef struct A {
2: int x;
3: }A_t;
4:
5: int main() {
6: A_t *a;
7: a = &(A_t());
8: return 0;
9: }

---------------------

When I use g++(2.96) to compile this program, it report an error at line 7.
Error Message is : main.cpp:7: parse error before `;'
But this program can be pass in VC6, who can tell me why?
thanks.

 

[Kevin Goodsell]

main.cpp
1: typedef struct A {
2: int x;
3: }A_t;

Please don't do this. struct tags are types in C++. This typedef
nonsense only obfuscates the code.

struct A_t
{
int x;
};

4:
5: int main() {
6: A_t *a;
7: a = &(A_t());

I would not expect this to compile. It looks like you are attempting to
take the address of a temporary. Any particular reason? I don't believe
it is legal to take a temporary's address, nor is it useful.

8: return 0;
9: }

---------------------

When I use g++(2.96) to compile this program, it report an error at line 7.
Error Message is : main.cpp:7: parse error before `;'
But this program can be pass in VC6, who can tell me why?
thanks.

My best guess is that VC6 is wrong.

-Kevin

 

[Alan Morgan]

Please don't do this. struct tags are types in C++. This typedef
nonsense only obfuscates the code.

struct A_t
{
int x;
};


I would not expect this to compile. It looks like you are attempting to
take the address of a temporary. Any particular reason? I don't believe
it is legal to take a temporary's address, nor is it useful.

Gcc issues a warning if you write the line like so:

7: a = &A_t();

Any idea why it gives a warning for one and a parse error for the other?

Alan

 

[Ron Natalie]

7: a = &(A_t());

When I use g++(2.96) to compile this program, it report an error at line 7.
Error Message is : main.cpp:7: parse error before `;'
But this program can be pass in VC6, who can tell me why?
thanks.

VC6 is wrong. A_t() yields an rvalue. You can not apply & to it.