v0.40: Create exercises. Challenge the community.

sum_range

Your mission

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.

See it in action

sum_range(a, a + 5) with a = {3, 8, 1, 9, 4}

Expected result

Your checklist

For your own tracking. Tests grade your code.

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.

More examples

sum_range(a + 1, a + 4) with a = {10, 20, 30, 40, 50}

Expected result

sum_range(a, a) with a = {7, 7, 7}

Expected result

Constraints

Expected files

sum_range.c

Allowed functions

None. Write every helper yourself.

sum_range

Pointers

Your mission

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.

See it in action

sum_range(a, a + 5) with a = {3, 8, 1, 9, 4}

Expected result

Your checklist

For your own tracking. Tests grade your code.

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.

More examples

sum_range(a + 1, a + 4) with a = {10, 20, 30, 40, 50}

Expected result

sum_range(a, a) with a = {7, 7, 7}

Expected result

Constraints

Expected files

sum_range.c

Allowed functions

None. Write every helper yourself.

Tests

Run the tests to grade your code

Build your code, then check each test here. Open a result to inspect its output.

Build

01Whole arrayWaiting

02Range of one elementWaiting

03Array holding a single integerWaiting

04Empty range at the startWaiting

05Empty range one past the endWaiting

06Empty range in the middleWaiting

07Subrange in the middleWaiting

08Range that stops before the endWaiting

09Subrange at the endWaiting

10The integer at last is left outWaiting

11Negative values onlyWaiting

12Positives and negatives that cancel outWaiting

13Every value is zeroWaiting

14Total close to the int maximumWaiting

15Total close to the int minimumWaiting

sum_range

Your mission

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.

See it in action

sum_range(a, a + 5) with a = {3, 8, 1, 9, 4}

Expected result

Your checklist

For your own tracking. Tests grade your code.

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.

More examples

sum_range(a + 1, a + 4) with a = {10, 20, 30, 40, 50}

Expected result

sum_range(a, a) with a = {7, 7, 7}

Expected result

Constraints

Expected files

sum_range.c

Allowed functions

None. Write every helper yourself.

sum_range

Pointers

Your mission

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.

See it in action

sum_range(a, a + 5) with a = {3, 8, 1, 9, 4}

Expected result

Your checklist

For your own tracking. Tests grade your code.

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.

More examples

sum_range(a + 1, a + 4) with a = {10, 20, 30, 40, 50}

Expected result

sum_range(a, a) with a = {7, 7, 7}

Expected result

Constraints

Expected files

sum_range.c

Allowed functions

None. Write every helper yourself.

Tests

Run the tests to grade your code

Build your code, then check each test here. Open a result to inspect its output.

Build

01Whole arrayWaiting

02Range of one elementWaiting

03Array holding a single integerWaiting

04Empty range at the startWaiting

05Empty range one past the endWaiting

06Empty range in the middleWaiting

07Subrange in the middleWaiting

08Range that stops before the endWaiting

09Subrange at the endWaiting

10The integer at last is left outWaiting

11Negative values onlyWaiting

12Positives and negatives that cancel outWaiting

13Every value is zeroWaiting

14Total close to the int maximumWaiting

15Total close to the int minimumWaiting

v0.40: Create exercises. Challenge the community.

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