Objective

Write a function that adds up the integers of a range described by two pointers, where the second one marks the slot just after the last integer to read.

Steps

• first points at the first integer of the range. last points one slot past the last integer of the range.
• Add every integer from first up to last, last excluded, and return the total. There is no length parameter, so move through the range with pointer arithmetic.
• For an array a holding 5 integers, sum_range(a, a + 5) covers the whole array, while sum_range(a + 1, a + 4) covers a[1], a[2] and a[3] only.
• Never read the integer at last. It can sit one slot past the end of the array, where nothing belongs to you.
• Return 0 when first equals last: that range is empty.
• Assume last is first or a position after it, and that every total fits in an int, so you have no overflow to guard against.
• Print nothing. The return value is what gets checked.

Objective

Write a function that adds up the integers of a range described by two pointers, where the second one marks the slot just after the last integer to read.

Steps

• first points at the first integer of the range. last points one slot past the last integer of the range.
• Add every integer from first up to last, last excluded, and return the total. There is no length parameter, so move through the range with pointer arithmetic.
• For an array a holding 5 integers, sum_range(a, a + 5) covers the whole array, while sum_range(a + 1, a + 4) covers a[1], a[2] and a[3] only.
• Never read the integer at last. It can sit one slot past the end of the array, where nothing belongs to you.
• Return 0 when first equals last: that range is empty.
• Assume last is first or a position after it, and that every total fits in an int, so you have no overflow to guard against.
• Print nothing. The return value is what gets checked.