C++ Array vs vector

Question

when using C++ vector, time spent is 718 milliseconds, while when I use Array, time is almost 0 milliseconds.

Why so much performance difference?

int         


        

Answer 1

When profiling code, make sure you are comparing similar things.

vector v(size*size); 

initializes each element in the vector,

int arr[size*size]; 

doesn't. Try

int arr[size * size];
memset( arr, 0, size * size );

and measure again...