const modifier at end of signature

Code:

---

unsigned int Drib::nextBird(unsigned int visibility)//having a const here screws things up
{
    return dielema.nextBird(visibility);
}

---

dielema is an instance of a class that I wrote. When I try to call this method above, if it still had the const, my compiler would give me an error thinking that I'm passing visibility by reference.

I thought declaring a method as const just means that it's not going to change any of the private data members?

Is "nextBird" (and every function it calls) declared with "const" at the end also? Also, "nextBird" (and every function it calls) cannot modify the object (this)

no it's not declared const, but it is not a mutator method (nor is any other it calls)

what reasoning is used to make it think that whenever I call the method declared as const that I'm passing it references?

Then declare it and every function it calls as const, or remove "const" from the single function thats causing problems above.

Im not sure why it would complain about references, I havent done anything like this in a while. What is the exact error message?

Also, if this is a recursive call, its infinite recursion, so you should fix that.

Marking a method as const means that it won't modify any member variables of that object. I'm assuming dielema is a member variable of the class? If that's the case, then you cannot call a non-const member variable of the dielema class because non-const functions are allowed to modify the state of the class.

GoodGuy.cpp

Code:

---

unsigned int Drib::nextBird(unsigned int visibility)//having a const here screws things up
{
    return dielema.nextBird(visibility);
}

---

GoodGuy.h
[CODE]
#ifndef LINKED_LIST_INCLUDED
#define LINKED_LIST_INCLUDED
#include "LinkedList.h"
#endif

const unsigned int SECONDS_WORKED = 60*60*10;//10 hour work day
const unsigned int RATE = 8;//cages 8 birds in an hour
const unsigned int MAX_BIRDS_CAGED = SECONDS_WORKED*RATE/60;
const unsigned int TREE_HEIGHT = 20;//20 branches on the tree
const unsigned int COLUMNS = 2;
const unsigned int MIN_TIME = 7;
const unsigned int MAX_TIME = 10;

class Drib
{
public:
Drib();
unsigned int getSecondsWorked() const;
unsigned int search(unsigned int maxVisibility, bool algorithm);
void erase(unsigned int position);
unsigned int nextBird(unsigned int visibility);//use to be const
unsigned int getBranch(unsigned int bird);
unsigned int getFirst() const;
void remove(unsigned int location);

private:
unsigned int properTime;
unsigned int rows;
List dielema;
unsigned int getRandomNumber(int nLow, int nHigh) const;
double unifRand();

};

LinkedList.cpp

Code:

---

unsigned int List::nextBird(unsigned int t)
{
    NodePtr temp = head;
    unsigned int current = 0;
    while(temp->next != NULL)
    {
        if((temp->time+BIRD_LAST_IN_CAGE) >= t)
            return current;
        else
        {

/*the following 2 lines modify data members*/

            List::erase(current);
            birdsDied++;
        }
        current++;
    }
}

---

when I compile this I get:
error: no matching function for call to `List::nextCagedBird(unsigned int&) const'
note: candidates are: unsigned int List::nextCagedBird(unsigned int) <near match>

so what's the deal with the &

Drib.cpp:75: error: no matching function for call to `List::nextCagedBird(unsigned int&) const'
LinkedList.cpp:201: note: candidates are: unsigned int List::nextCagedBird(unsigned int) <near match>

another question, when I try to compile all I get is this:
>C:\MinGW\bin\g++ -pedantic -Os main.cpp -o main.exe
C:\DOCUME~1\Brendon\LOCALS~1\Temp/ccJ3tb2i.o:main.cpp:(.text+0x43e): undefined reference to `BadGuy::BadGuy()'
collect2: ld returned 1 exit status
>Exit code: 1

Quote:

---

Originally Posted by help_seed

I thought declaring a method as const just means that it's not going to change any of the private data members?

---

No, it means that the method promises to not change any members, not just private ones but public and protected as well (excluding mutable).
It wont allow you to make that promise if it sees that the function is calling a method which itself doesn't also make that promise.

Quote:

---

when I compile this I get:
error: no matching function for call to `List::nextCagedBird(unsigned int&) const'
note: candidates are: unsigned int List::nextCagedBird(unsigned int) <near match>

so what's the deal with the &

---

The & is completely irrelevant. Since there is no matching function, how is the compiler supposed to figure out whether that missing function takes the argument by reference or not?