Is this bad C++ code?

[Pyrolistical]

Is this bad code?

void foo(int n) {
  float bar[n];
  ...
}

That code compiles and works, but I thought you are suppose to do something like:

float * bar = new float[n];

Why does it let you compile and use those arrays if your not suppose to do that?

 

[Twister]

The first example should not compile, or at least should not work.
The second way is the only correct way to allocate dynamic memory for your given situation.

 

[Pyrolistical]

Well, that's werid.

Here I am using gcc 3.3.1 with -Wall...but it compiles and even works (must be overwriting random bits of memory heh)

 

[mikeblas]

Yes, it's bad code. The size of an array declaration must be a constant expression.

GCC has an extension that lets this code compile. I don't know of a way to turn it off, but I'm not a big-tim GCC user.

Here's a recent thread where the question came up before.

 

[Lews_Therin]

Well, that's werid.

Here I am using gcc 3.3.1 with -Wall...but it compiles and even works (must be overwriting random bits of memory heh)

It will work, but you shouldn't use it. If you want strict checking, try adding the -ansi and -pedantic flags.

 

[mikeblas]

Looks like -pedantic catches it.

 

[Shadow2531]

Yeh, you can do:

g++ -Wall -Wextra -pedantic -ansi file.cpp -o file

If the gcc version is a little old then, -W instead of -Wextra.