return value of std::find of an vector of custom class objects

Question

i want to work with the return value of std::find but it wont compile.

error: no match for 'operator=' in 'it = __gnu_cxx::operator!= >(((const __gnu_cxx::__normal_iterator >)(& std::find<__gnu_cxx::__normal_iterator >, Dummy>(dummylist.std::vector<_Tp, _Alloc>::begin >(), dummylist.std::vector<_Tp, _Alloc>::end >(), ((const Dummy)(& Dummy(tempArray[0])))))), ((const __gnu_cxx::__normal_iterator >)(& dummylist.std::vector<_Tp, _Alloc>::end ())))'

#include <iostream>
#include <cstring>
#include <stdlib.h>
#include <vector>
#include <algorithm>
#define SIZEDATASET 1

using namespace std;

class Dummy
{
public:
    Dummy(int Name)
    {
        this->Name = Name;
        this->v0 = 0;
        cout << "Hello, im new " << this->Name << endl;
    }
    ~Dummy()
    {
        cout << "Im done " << this->Name << endl;
    }
    int Name;
    int v0;
};

bool operator== (const Dummy &D0, const Dummy &D1)
{
    return D0.Name == D1.Name;
}


void printClass(vector<Dummy>:: iterator D)
{
    cout << "Name: " << (D)->Name << endl;
    cout << "v0: " << (D)->v0 << endl;
    return;
}

int main()
{
    string str0 = "1;3;2;2;2;4;";
    string str1 = ";";
    string str2;
    int ende = 0;
    int start = 0;
    int length = 0;
    int tempArray[SIZEDATASET] = {0};
    int _switch = 0;
    int i;
    vector<Dummy> dummylist;
    vector<Dummy>:: iterator it;
    Dummy *DummyTemp;


    while((unsigned int)(ende = str0.find(str1,ende))!= std::string::npos)
    {
        length = ende - start;
        str2 = str0.substr(start,length);
        ende+= str1.size();
        start=ende;

        tempArray[_switch]= atoi(str2.c_str());
        _switch++;

        if((_switch%=SIZEDATASET) == 0)
        {
            for(i=0; i<SIZEDATASET; i++)
            {
                cout << tempArray[i] << " ";
            }
            cout << endl;



/*this line*/ if((it = find(dummylist.begin(),dummylist.end(),Dummy(tempArray[0])) != dummylist.end())) /* why u not work?*/
            {
                cout << "match " << endl;
                it->v0++;
            }
            else
            {
                cout << "no match" << endl;
                dummylist.push_back(Dummy(tempArray[0]));
                DummyTemp = &(dummylist.back());
                DummyTemp->v0++;
            }
        }

    }
    it = dummylist.begin();
    while(it != dummylist.end())
    {
        printClass(it);
        it++;
    }
    dummylist.clear();


    return 0;
}

Later the program will receive a string of data(str0) cut it and store it in temporary(tempArray). Then I check(using find) if I already got a set data with the same Name (tempArray[0] represent the name of the dataset). If this is not the case I create a new class with the data and store it in a vector(dummylist). If I found a dataset with the same name in my vector I want to change the values of the existing class in the vector by using the return value of find().

The function find() returns an iterator and "it" is one so I don't know why the error appears.

sorry for my english.

Regards, Dominic

edit: notice that im not struggle with find() itself like in this post.

You misplaced your parentheses in the condition. (You have `((a = b != c))` but you intended `((a = b) != c)`.) Voting to close as a typo. — molbdnilo, Jun 10 '16 at 08:19
When you have problems like this, make your code more verbose and explicit by not doing too much on each line. Make it work like that first and then combine to make the code more unreadable ;) — thorsan, Jun 10 '16 at 08:23
Dont feel stupid, take it as an experience, you are learning. — thorsan, Jun 10 '16 at 08:24
downvoted. `/* why u not work?*/` should be accompanied with a `ლ(ಠ_ಠლ)` — UmNyobe, Jun 10 '16 at 08:39
You mean, it should be accompanied with a ( ͡° ʖ̯ ͡°) ?? — pradyot, Jun 10 '16 at 08:46

score 1 · Accepted Answer · answered Jun 10 '16 at 08:21

Your if statement has got its bracketing wrong: you're trying to assign the result of a comparison operation, instead of comparing the result of an assignment. Change:

if((it = find(dummylist.begin(),dummylist.end(),Dummy(tempArray[0])) != dummylist.end()))

To:

if((it = find(dummylist.begin(),dummylist.end(),Dummy(tempArray[0]))) != dummylist.end())

return value of std::find of an vector of custom class objects

1 Answers1