What is better for runtime of array size during runtime?

Question

Which way is better an why(complete info)

#include <iostream>
using namespace std;

int main(){
/*Using Dynamic memory allocation*/
int Dsize;
int *arrnm;
cin>>Dsize;

arrnm = new int[Dsize];
/*Using a other way*/

int size;
cin>>size;
int arrname[size];

return 0;
}

Answer 1

The standard way to initialize an array whose size is known only during runtime, is dynamic memory allocation.

int* arr = new int[n];

Some compilers may not accept

int arr[n];

where n is a variable, since the expression by right requires a constant for size declaration.

https://stackoverflow.com/questions/30499228/c-array-size-must-be-an-const-expression

https://stackoverflow.com/questions/9219712/c-array-expression-must-have-a-constant-value

Answer 2

Hatsy Rei Thanks