Array size at run time without dynamic allocation is allowed?

Question

I\'ve been using C++ for a few years, and today I saw some code, but how can this be perfectly legal?

int main(int argc, char **argv)
{
    size_t size;
             


        

Answer 1

This is known as VLAs (variable length arrays). It is standard in c99, but gcc allows it in c++ code as an extension. If you want it to reject the code, try experimenting with -std=standard, -ansi and -pedantic options.

Answer 2

You can give size to an array dynamically in if you are using Dev-Cpp compiler I have tried it and got no error but on visual c++ and visual studio compilers it is not possible. I think the reason is that dev-c++ assigns a positive number to the uninitialized int and when we give it a number it is replaced by the given one. but perhaps other compilers give null to uninitialized variables.