Answer:
// Assume that all variables a, n, temp have been declared.
  // Where a is the array, n is the array length, temp is a temporary
  // storage location.
  // Cycle through the array a.
  // By the time the loop gets halfway,
  // The array would have been reversed.
  // The loop needs not get to the end of the array.
  // Hence, the loop ends halfway into the array i.e n/2.
  for (int k = 0; k < n / 2; k++) {
    
  	// Swap first and last, second and next-to-the-last and so on
  	temp = a[k];
  	a[k] = a[n - k - 1];
  	a[n - k - 1] = temp;
  }
Explanation:
Carefully go through the comments in the code.
Hope this helps!