can size of array be determined at run time in c?

Question

As I know, an array needs to have a specific size before compiling time in c.

I wonder why this code still works?

int s;
printf(\"enter the array si         


        

Answer 1

You are confusing two things here.

1) Determining the size of an already allocated array (which your title implies): divide sizeof() for the total by the size of one (say, the first) element:

 sizeof(a)/sizeof(a[0])

2) Dynamically allocating memory as your question asks:

 int *a = (int*)malloc( s * sizeof(int) );