Answers for "c++ array variable size"

array length c++

#include <iostream>
using namespace std;

#define size(type) ((char *)(&type+1)-(char*)(&type))

int main(){
  int arr[5] = {1, 2, 3, 4, 5};
  cout << size(arr) / size(arr[0]) << endl; //returns 5
  //alternatively
  cout << sizeof(arr) / sizeof(int) << endl; //returns 5
}

c++ array with variable size

int n = 10;
double* a = new double[n]; // Don't forget to delete [] a; when you're done!