yo, im taking a data structures class and my first assignment has to do with templating and some simple functions to make, but im sorta stuck on how to do some things. I'll be in vc!
#(flimsynimsy) i need some simple c++ help in vc PRETTY PLEASE
fallow totem
maiden raftBOT
(flimsynimsy) i need some simple c++ help in vc PRETTY PLEASE
maiden raftBOT
yo, im taking a data structures class and my first assignment has to do with tem...
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civic urchin
i can probably help a bit but not available to vc if you want to just ask whatever questions you have
fallow totem
i can probably help a bit but not available to vc if you want to just ask whatev...
sweet
so i have this rn
im not sure how to pass the datatype in the function
actually nvm, i dont think that's my probelm
im just trying to remove the item from the list, and then shift everything back one
i had an idea to just move the "empty" space in the array onto the end of the list, but i thought maybe i could just recreate the container without the "empty" item in the first place?
made a small mistake with i and j in the second for loop btw
eh, whatever, i think ik a better way
remove first occurrence of item, shift items to fill empty position
this is what remove_item is supposed to do btw
civic urchin
i assume Container is like an array based list or something?
fallow totem
template <class T, int N>
class Container
{
public:
using value_type = T;
void add_item(T item); // output "container full", if add_item cannot add
void remove_item(T item); // remove first occurrence of item, shift items to fill empty position
T get_item(int index); // throw an std::string if index out of bounds
bool empty(); // check if Container is empty
void clear(); // clear all contents , assign value_type
constexpr int size(); // return current number of elements in container
T* begin();
T* end();
private:
int _size = 0; // number of elements in the Container
T container[N]; // a Container of length/size N
}
this is container
civic urchin
so think about it like this, say you find the item to remove, and its at index k
how do you move everything 1 to the left?
fallow totem
well
this is what im doing rn
(or trying to do)
template <class T, int N>
void Container <T, N >::remove_item(T item) {
for (int i = 0; i < _size; i++) {
if (container[i] == item) {
container[i] = T();
//remake the list without the empty gap
for (int j = i; j < _size; j++) {
container[j] = container[j + 1];
}
_size--;
break;
}
}
}
i think this works
oh wait
there we go
civic urchin
you don't need to empty out the container[i] because you can just overwrite it with container[i+1]
civic urchin
and then you empty out the very last element that exists
because you're setting the one before to equal the one to the right of it
fallow totem
ohhhh right
fallow totem
and then you empty out the very last element that exists
also, is there really a need for this? it outputs correctly rn
civic urchin
i would wager if you print out container[_size] it would still return the value that used to exist instead of being null
fallow totem
ill try it out
civic urchin
the last element should be at container[_size-1] because 0 index
fallow totem
well also, i do subtract the size value as well
so you'll only be able to check by unconventional means
cout << container[_size];
if i do this, it just returns empty
but maybe that's because im removing the value Red , which is in between the two values?
fallow totem
and then you empty out the very last element that exists
so you're thinking something like this?
template <class T, int N>
void Container <T, N >::remove_item(T item) {
for (int i = 0; i < _size; i++) {
if (container[i] == item) {
//remake the list without the empty gap
for (int j = i; j < _size; j++) {
container[j] = container[j + 1];
}
container[_size] = T();
_size--;
break;
}
}
}
oh wait no that should be fine how you have since the last element would be copying the termination back one too
fallow totem
so there's no need to clear out the last element?
civic urchin
hold on give me a second to get back into c++ mindset lol
fallow totem
lol
i think it's fine
because it's just being overrided
so there's no need to clear anything
civic urchin
yeah i was thinking about char string arrays where they are terminated with a special character, i think technically for safety you'd want to remove the last value, but if the other operations are bounded by _size then it doesn't really matter
(in this case)
fallow totem
ig ill do it for safety
so there's another function they want me to implement too
bool empty(); // check if Container is empty
couldn't i literally just do
template <class T, int N>
bool Container <T, N >::empty() {
if (_size == 0) {
return true;
}
return false;
}
should be able to just return _size == 0
fallow totem
oh ok cool lol
final implementation
T get_item(int index); // throw an std::string if index out of bounds
ill try to do it myself rq
hmm
civic urchin
for the empty() it's like denizen's common mistakes,guide, it parses down to if true return true so just return the comparison directly
fallow totem
true true
this is what im doing for the get_item function btw
template <class T, int N>
T Container <T,N>::get_item(int index) {
if (index > _size){
cout << "Index out of bounds!";
return;
}
return container[index];
}
but i dont think it's working
civic urchin
remember arrays are 0 indexed
fallow totem
oh right
so i gotta check for _size-1
still has problems though
this is what im doing to check it in main
cout << "container_of_strings.get_item()=" << container_of_strings.get_item(3) << "\n";
oh its because of the empty return
fallow totem
yea i fixed it
so im just doing this now return "Index out of bounds!";
but now the if check is broken, so imma print out the index and _size value
fallow totem
wdym where
civic urchin
instead of returning in the if checking for index oob
throw the string instead of returning the string
because that's what it asks you to do lol
fallow totem
i dont get what it means by "throw the string"
civic urchin
literally instead of return use throw
fallow totem
oh lol
template <class T, int N>
T Container <T,N>::get_item(int index) {
if (index > _size-1){
throw "Index out of bounds!";
}
return container[index];
}
so just this?
civic urchin
throw implies an error, and normally you wouldnt throw a string but instead throw an exception
but always stick to what the assignment asks lol
you'd need to throw new std::string("index oob"); or if you're using std namespace then just throw new string("index oob");
fallow totem
yea im using namespace
what's the difference between throw "oob"; and throw new string("oob");?
is it just better practice?
civic urchin
without the string i believe it will create a bare char[] instead
while a string is a class
civic urchin
no, the throw ends the execution
fallow totem
ah
ugh i accidentally enabled this annoying debug thing in vscode now it doesn't even debug properly
idk how to fix this shit
like- it does this
whereas i just dont want it to debug and i want it to tell me the errors
civic urchin
that is visual studio, not vscode
fallow totem
oh yea my fault
vscode
how do i fix it
im getting so annoyed 😭
template <class T, int N>
T Container <T,N>::get_item(int index) {
if (index > _size){
throw new string("Index out of bounds!");
}
return container[index];
}
i dont think this is working
fallow totem
```c++
template <class T, int N>
T Container <T,N>::get_item(int index) {
if...
yo @civic urchin im tryna understand how to fix this, any ideas?
ohhhhh wait
i think it's because of the throw command that the error is happening
civic urchin
probably, it should be in a try catch
lavish baneBOT
probably, it should be in a try catch
fallow totem
i dont think that's what he's asking for though
civic urchin
but i dont think it actually HAS to be because c++ lets you do wild shit sometimes and its just your ide getting mad that you're doing bad programming
fallow totem
wait maybe my professor wants the oob thing to throw an exception like that?
civic urchin
this is where it gets kind of hard because i have no idea what youve been taught
i would probably look through his examples and find what he is expecting you to do
civic urchin
email him and ask! or a TA
fallow totem
true
civic urchin
maybe try putting the return into an else and see if that satisfies the ide
fallow totem
i tried to
civic urchin
yeah i got nothing for that, i just tried it and it let me do it here
wait it should just work like that yeah, did you actually try just compiling the program isntead of debugging it
the debugger will catch it because its literally throwing an error, but it will still compile and work as intended if you aren't giving it a value that errors
fallow totem
so how do i fix?
this is what im getting rn
i dont understand this bro
i think im going crazy
how do i compile it?
civic urchin
its because T container[N]; isn't initialized with a value, but that shouldn't stop you from compiling
civic urchin
at the top click the green play button
there's one that's attached to the debugger and one that launches without the debugger
civic urchin
that likely means something with the amount of memory allocated to the container array was not enough
fallow totem
but like- why now all of a sudden
civic urchin
when you add_item is it trying to add another int to an already full container?
fallow totem
well that's why we have a check for it
template <class T, int N>
void Container <T, N >::add_item(T item) {
if (_size >= N) {
cout << "\nContainer full!";
return;
}
container[_size] = item;
_size++;
}
and for some reason it doesn't exit when i press the "enter any key to exit"
ok so the error resides somewhere in here
found it
it's in remove_item
bruh i found the issue
shouldn't have done this
civic urchin
oh yeah it should be _size-1