Your mission

Write int_vec_push, which appends value to a heap array of int and moves the array to a block twice as large when it is full.

See it in action

5 pushes (10, 20, 30, 40, 50) on an empty array

push 10: ret=0 len=1 cap=4 moved
push 20: ret=0 len=2 cap=4 same
push 30: ret=0 len=3 cap=4 same
push 40: ret=0 len=4 cap=4 same
push 50: ret=0 len=5 cap=8 moved
[10,20,30,40,50]

push 4 on a full array {1, 2, 3} with cap 3

push 4: ret=0 len=4 cap=6 moved
[1,2,3,4]

push 9 on an array that cannot grow (malloc returns NULL)

ret=-1 data=same len=same cap=same values=7,8

Your checklist

• *data points to a block from malloc holding *len integers, with room for *cap. An empty array is *data == NULL, *len == 0 and *cap == 0.
• On success, value sits at index *len of the old count, every earlier integer keeps its index and value, *len grows by 1, and the function returns 0.
• When *len equals *cap on entry, the array moves to a new block from malloc. The new capacity is 4 when *cap is 0, and *cap * 2 otherwise. The old block is released, and *data and *cap describe the new one.
• When *len is below *cap, value goes into the current block, which stays where it is.
• Tests print ret, len and cap after each push, moved when *data changed and same when it did not, then the integers. Every test frees *data at the end and runs under a memory checker.
• If malloc fails, return -1 and leave *data, *len, *cap and the integers exactly as they were.

Your mission

Write int_vec_push, which appends value to a heap array of int and moves the array to a block twice as large when it is full.

See it in action

5 pushes (10, 20, 30, 40, 50) on an empty array

push 10: ret=0 len=1 cap=4 moved
push 20: ret=0 len=2 cap=4 same
push 30: ret=0 len=3 cap=4 same
push 40: ret=0 len=4 cap=4 same
push 50: ret=0 len=5 cap=8 moved
[10,20,30,40,50]

push 4 on a full array {1, 2, 3} with cap 3

push 4: ret=0 len=4 cap=6 moved
[1,2,3,4]

push 9 on an array that cannot grow (malloc returns NULL)

ret=-1 data=same len=same cap=same values=7,8

Your checklist

• *data points to a block from malloc holding *len integers, with room for *cap. An empty array is *data == NULL, *len == 0 and *cap == 0.
• On success, value sits at index *len of the old count, every earlier integer keeps its index and value, *len grows by 1, and the function returns 0.
• When *len equals *cap on entry, the array moves to a new block from malloc. The new capacity is 4 when *cap is 0, and *cap * 2 otherwise. The old block is released, and *data and *cap describe the new one.
• When *len is below *cap, value goes into the current block, which stays where it is.
• Tests print ret, len and cap after each push, moved when *data changed and same when it did not, then the integers. Every test frees *data at the end and runs under a memory checker.
• If malloc fails, return -1 and leave *data, *len, *cap and the integers exactly as they were.