Confused between Temporal and Spatial locality in real life code

Question

I was reading this question, I wanted to ask more about the code that he showed i.e

for(i = 0; i < 20; i++)
    for(j = 0; j < 10; j++)
        a[i] = a[i]         


        

Answer 1

The outer loop is an example of spacial locality. It sequentially increments the address the inner for-loop calls.

The inside loop demonstrates temporal locality. The exact same memory address is accessed ten times in a row, and multiplied by j each time.

As for your first two questions, both i and j (loop counters) are very good examples of temporal locality.

Locality is a measure applied by the cache to minimize the calls to memory. If an instruction needs to know the value of a memory address which is not already in the cache, it will access the memory and store all surrounding memory locations in the cache as well.