CODEWITHSUNDEEP
c++vectorstl
Happy Mittal
Happy Mittal

Reputation: 3747

Erase object from vector in C++

I am trying to erase an object from a vector in C++, but it is giving a strange (and long) error. I have written this : 

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

class foo
{
    int a;
    public:
    foo(int _a):a(_a){}
};

int main() {
    foo f1(5),f2(10);
    vector<foo> vec = {f1,f2};
    vec.erase(remove(vec.begin(),vec.end(),f1),vec.end()); // remove f1 (error)
    return 0;
}

The exact error I get is here.
On the other hand, when I create a vector of int and then try to remove an integer from that vector, it works fine.

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int main() {
    vector<int> vec = {5,10};
    vec.erase(remove(vec.begin(),vec.end(),5),vec.end()); // works fine
    return 0;
}

I am not sure why there is an error in first case.

Upvotes: 0

Views: 196

Answers (1)

Mohit Jain
Mohit Jain

Reputation: 30489

For std::remove your class foo should contain operator == or you should explicitly pass a comparison function. For standard types (int for example), comparison function is defined by language and thus it compiles without an error.

One example for operator == can be:

class foo
{
    ...
    bool operator ==(const foo &t) const { return t.a == a; }
};

Upvotes: 5

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