Didn't understand the concept taught in this video completely

#1

I’m not able to map out the working of ampersand operator in the bubble_sort function in this video. Can you please explain this concept in a bit more detail. Thankyou

#2

Hey @chaturvedia336
This thread discuss that :Sorting/sort function/comparator

#3

I read this thread, it’s still a bit unclear. The problem is that in the function declaration line of bubble_sort we have used pass by reference, while calling the bubble_sort function in main we are directly passing the comparator function as an argument.

#4

This is what I’m having difficulty understanding

#5

Hey,
Let me explain you in simple terms
int &i =j;
Here i is an alias to j i.e they both are same but two different names . Like we can have one official name and one nick name
Now how we pass argument in function using above concept:
solve(int &i){
}
main(){

solve(j);
}
This is how we pass j and receive it in i.

Similarly here we are passing function instead of integer and collecting it in an alias .

#6

That is exactly what I’m asking, why are we even using the alias if they both are same with two different names.
Can we discard &cmp altogether and just use compare instead, in the function declaration line as well as the function call line for bubble_sort in main() ?

#7

Yes we can
bool compare(int a,int b){
return a<b;
}

void solve(bool (cmp)(int a,int b)){
cout<<cmp(5,6);
return ;
}

int main() {
solve(compare);
}

This will work fine ,We use &(i.e pass by reference) so that memory is not wasted.

#8

This answered a lot of what I asked. Just one more thing, in the declaration statement of solve(), can we pass the function compare directly[like you did while calling solve() in main()], instead of what you’re doing[i.e, declaring the placeholder cmp()]. And if not, can you please tell why? … Thanks & Regards

#9

Hey
I am not able to understand what you are asking so please give an example for the same

#10

For example, like in the example that you mentioned [in which you used solve() ] can I write it as—
bool compare(int a,int b){
return a<b;
}

void solve(compare){
cout<<compare(5,6);
return ;
}

int main() {
solve(compare);
}

#11

Basically I’m asking whether we can directly pass the compare() as a parameter in our solve() or not.Please explain this. Thanks & Regards.

#12

Hey yes we can do that but collecting parameter in you code segment is not correct.

bool compare(int a,int b){
return a<b;
}

void solve(bool compare(int a,int b)){
cout<<compare(5,6);
return ;
}

int main() {
solve(compare);

}

This is the correct implementation of the same

#13

I did not understand this line. Can you please elaborate?

#14

This is the correct format to collect compare. and not void solve(compare)

#15

Correct format as in this is the syntax?

#16

yeah I meant correct syntax

#17

So basically we can do void solve(compare), but void solve(bool compare(int a, int b)) is the correct syntax , hence we use the latter…
Correct?

#18

If you will write this ,this will give you compilation error

So the correct syntax to receive a function in argument is this

I hope this is what you are asking.

#19

Okay. Got that…
Thanks a lot for the help. Much appreciated :slight_smile:

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#20

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