Sort a in place by insertion and hand the whole array to report after every insertion, so the caller can watch the sorted prefix grow one slot at a time.

• insertion_steps(a, n, report) puts the n integers stored at a in ascending order. The sort happens in the buffer you were given, and the function returns nothing.
• Walk the indices from 1 to n - 1. At each index you lift the value sitting there and drop it into its place inside the sorted prefix on its left, sliding every larger value one slot to the right.
• Call report(a, n) once at the end of each of those steps, the very first one included. After the k-th call, a[0] through a[k] hold the first k + 1 original values in ascending order and every slot after them still holds what it held on entry.
• That comes out to exactly n - 1 calls for a non-empty array. n of 0 and n of 1 both produce zero calls: there is no index 1 to insert.
• A value that is already in its place still counts as a step. Report it anyway.
• Equal values all stay in the result, none of them get dropped. Nothing before a[0] or after a[n - 1] may be read or written.
• report is always a valid function pointer. You never have to check it for NULL.
• insertion_steps prints nothing of its own. Every line below is printed by the report it was handed, so the format is not your problem. The examples use a report that prints one step: line per call and a final calls: count; other checks hand you a report that prints something else, or nothing at all. A few of them echo the buffer afterwards as arr: ....

Sort a in place by insertion and hand the whole array to report after every insertion, so the caller can watch the sorted prefix grow one slot at a time.

• insertion_steps(a, n, report) puts the n integers stored at a in ascending order. The sort happens in the buffer you were given, and the function returns nothing.
• Walk the indices from 1 to n - 1. At each index you lift the value sitting there and drop it into its place inside the sorted prefix on its left, sliding every larger value one slot to the right.
• Call report(a, n) once at the end of each of those steps, the very first one included. After the k-th call, a[0] through a[k] hold the first k + 1 original values in ascending order and every slot after them still holds what it held on entry.
• That comes out to exactly n - 1 calls for a non-empty array. n of 0 and n of 1 both produce zero calls: there is no index 1 to insert.
• A value that is already in its place still counts as a step. Report it anyway.
• Equal values all stay in the result, none of them get dropped. Nothing before a[0] or after a[n - 1] may be read or written.
• report is always a valid function pointer. You never have to check it for NULL.
• insertion_steps prints nothing of its own. Every line below is printed by the report it was handed, so the format is not your problem. The examples use a report that prints one step: line per call and a final calls: count; other checks hand you a report that prints something else, or nothing at all. A few of them echo the buffer afterwards as arr: ....