v0.40: Create exercises. Challenge the community.

opaque_meter

Your mission

Implement an allocated counter whose fields stay private to meter.c.

See it in action

meter *m = meter_create(9); meter_add(m, -4); meter_value(m)

Expected result

Your checklist

For your own tracking. Tests grade your code.

Write meter.h and meter.c.
Keep struct s_meter out of meter.h. The header exposes only the incomplete meter type and the four functions.
meter_create allocates one meter, stores initial, and returns NULL if allocation fails.
meter_destroy releases the meter. Passing NULL is valid.
meter_add adds amount to the stored value.
meter_value returns the stored value.
Each call to meter_create owns a separate allocation.
Use only malloc and free.

Constraints

Expected files

meter.hmeter.c

Allowed functions

mallocfree

Allowed headers

<stdlib.h>declares malloc and free

<stddef.h>defines NULL

opaque_meter

Headers and the preprocessor

Your mission

Implement an allocated counter whose fields stay private to meter.c.

See it in action

meter *m = meter_create(9); meter_add(m, -4); meter_value(m)

Expected result

Your checklist

For your own tracking. Tests grade your code.

Write meter.h and meter.c.
Keep struct s_meter out of meter.h. The header exposes only the incomplete meter type and the four functions.
meter_create allocates one meter, stores initial, and returns NULL if allocation fails.
meter_destroy releases the meter. Passing NULL is valid.
meter_add adds amount to the stored value.
meter_value returns the stored value.
Each call to meter_create owns a separate allocation.
Use only malloc and free.

Constraints

Expected files

meter.hmeter.c

Allowed functions

mallocfree

Allowed headers

<stdlib.h>declares malloc and free

<stddef.h>defines NULL

Tests

Run the tests to grade your code

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

Build

01Keeps the initial valueWaiting

02Adds a signed amountWaiting

03Instances keep separate stateWaiting

04Destroy accepts NULLWaiting

05Memory checkWaiting

opaque_meter

Your mission

Implement an allocated counter whose fields stay private to meter.c.

See it in action

meter *m = meter_create(9); meter_add(m, -4); meter_value(m)

Expected result

Your checklist

For your own tracking. Tests grade your code.

Write meter.h and meter.c.
Keep struct s_meter out of meter.h. The header exposes only the incomplete meter type and the four functions.
meter_create allocates one meter, stores initial, and returns NULL if allocation fails.
meter_destroy releases the meter. Passing NULL is valid.
meter_add adds amount to the stored value.
meter_value returns the stored value.
Each call to meter_create owns a separate allocation.
Use only malloc and free.

Constraints

Expected files

meter.hmeter.c

Allowed functions

mallocfree

Allowed headers

<stdlib.h>declares malloc and free

<stddef.h>defines NULL

v0.40: Create exercises. Challenge the community.

Meet Studio →

opaque_meter

Headers and the preprocessor

Your mission

Implement an allocated counter whose fields stay private to meter.c.

See it in action

meter *m = meter_create(9); meter_add(m, -4); meter_value(m)

Expected result

Your checklist

For your own tracking. Tests grade your code.

Write meter.h and meter.c.
Keep struct s_meter out of meter.h. The header exposes only the incomplete meter type and the four functions.
meter_create allocates one meter, stores initial, and returns NULL if allocation fails.
meter_destroy releases the meter. Passing NULL is valid.
meter_add adds amount to the stored value.
meter_value returns the stored value.
Each call to meter_create owns a separate allocation.
Use only malloc and free.

Constraints

Expected files

meter.hmeter.c

Allowed functions

mallocfree

Allowed headers

<stdlib.h>declares malloc and free

<stddef.h>defines NULL

Tests

Run the tests to grade your code

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

Build

01Keeps the initial valueWaiting

02Adds a signed amountWaiting

03Instances keep separate stateWaiting

04Destroy accepts NULLWaiting

05Memory checkWaiting