C++: Why does int array[size] work?

Question

I have started learning c++. I read that an array\'s size can only be set before run and dymanic arrays can be set during runtime. So I was expecting this to fail but it did

Answer 1

Be careful! Undefined integers are not guarenteed to be any value at all. Some compilers will default to 0, while others will use whatever garbage bits where already in memory. For this reason Visual Studio wouldn't even let me compile. Step through your code to see the allocated memory for score before you set the size variable. Likely size as it is compiled is a random integer from garbage memory, which means it can change every time you execute!

A C style array needs to know how much continuous memory to allocate. This allows for direct indexing, and other optimizations. As others have suggested, std::vector is what is the standard dynamic container in C++, which uses an array under the hood.