CODEWITHSUNDEEP
c++
SleepyKni1ght
SleepyKni1ght

Reputation: 1

"Identifier is undefined" error after I explicitly defined the method

I wrote the following code, composing of two classes, Item and Integer. Integer is derived from Item and has a value "data". I wrote a printAll method which is meant to print one by one the elements of an array containing pointers but when I try to implement the printAll method in the main function I am getting an error saying it is undefined even though I defined it using the print method in the Integer class above.

#include <iostream>
#include<string>
using namespace std;

class Item
{
public:
    // prints data
    virtual void print() = 0;

    // returns “INTEGER”
    virtual string getType() = 0;

    // Adds or concatenates the 2 data members. 
    // Throws an exception in case of a type mismacth 
    virtual Item* add(Item* item) = 0;
};

class Integer : public Item {
private:
    int data;

public:
    Integer(int i) {    //Constructor
        data = i;
    }

    void print() {
        cout << "Integer value is: " << data << endl;
    }

    string getType() {
        return "INTEGER";
    }

    Item* add(Item* item) {
        if (item->getType() == "INTEGER") {
            dynamic_cast<Integer*>(item)->data;
        }

        else {
            throw "Type Mismatch";
        }
    }

    void printAll(Item** items, int n) {
        for (int i = 0; i < n; i++) {
            items[i]->print();
        }
    }
};

void main()
{
    int n = 10;
    Item** integers = new Item * [n];
    Item** strings = new Item * [n];

    // populate lists
    for (int i = 0; i < n; i++)
    {
        integers[i] = new Integer(i);
    }

        printAll(integers, n);      // print integers

Upvotes: 0

Views: 551

Answers (1)

john
john

Reputation: 87959

The mistake is that you put printAll in the Integer class. Change your code like this

class Integer : public Item {
    ...
};

void printAll(Item** items, int n) {
    for (int i = 0; i < n; i++) {
        items[i]->print();
    }
}

If a method is in a class, then you must (explicitly or implicitly) provide an object to call that method on. You didn't do that which is why you got the error. But in this case printAll should not be in any class, it should just be a regular function that you can call without supplying an object.

Upvotes: 4

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