dynamic arrays error

[EssamTarik]

i was trying to make a dynamic array in this form :
int x;
cin>>x;
int ar[x];
my g++ (gcc) compiler on linux refused to create an array without a fixed size , however using the same code on windows on dev-cpp it was complied and executed , also it allowd me to create and use the dynamic array , i thought it was a compiler bug , however when i restarted and returned to g++ it compiled and executed the code although it never did before i tried the code on windows , how can that be and is it dangerous ?

[kbw]

It's a C99 feature that is not available in C++.

[MiiNiPaa]

It might work on some compilers without pedantic mode enable, but:
1) It isn't standard and unportable
2) It is not stack allocated.
3) There is more problems than benefits with it.

[EssamTarik]

the whole thing is , that the same compiler(gcc) that refused to compile this code before compiling it in dev-cpp , is now compiling it with no errors !!! , how can this be ?

[kbw]

he whole thing is , that the same compiler(gcc) that ...

By same do you mean GCC on Windows and Linux? They're likely to be different versions.

[EssamTarik]

no , i mean i used GCC to compile and it popped up errors , restarted and used the same GCC on the same operating system (consider it just restarted my machine) and suddenly it can now compile the same code !!!!