C++ expected constant expression

Question

#include 
#include 
#include 
#include 
#include 
using std::ifstream;
using namespace std;
         


        

Answer 1

Because it expected a constant expression!

Array dimensions in C (ignoring C99's VLAs) and C++ must be quantities known at compile-time. That doesn't mean just labelled with const: they have to be hard-coded into the program.

Use dynamic allocation or std::vector (which is a wrapper around dynamic array allocation) to determine array sizes at run-time.