Member Avatar for munitjsr2 
#include <iostream>
    #include <vector>
    #include <algorithm>

    using namespace std;

    class A
    {
          public :
          void getData(vector< A > &);
          void putData(vector< A > &);
      
          private :
                  int x;
                  char name[90];
    };
    vector< A > v;

    void A :: getData(vector< A > &Aref)
    {
         cout << "id = ";
         cin >> x;
         cout << "\nname = ";
         cin >> name;
 
    }

    void A :: putData(vector< A > &Aref)
    {
         cout << "size of vector is " << Aref.size()  << endl;
         for(int i=0; i < Aref.size(); i++)
         cout << Aref[i].x << " : " << Aref[i].name << endl;
         
         cin.ignore(numeric_limits< streamsize >::max(), '\n'); 
         cin.get();
    }
     

    int main()
    {
        for(int i=0; i < 3; i++)
        {
        v.push_back(A());
        v[0].getData(v);
        v[0].putData(v);
        }
        vector< A >::iterator beg = v.begin(), en = v.end();
        //v.erase( find(beg, en, v[1]) ); -->DOESN'T WORK
        return 0;   
    }

I have used this
v.erase( find(beg, en, v[1]) ); (Line 48)
to search and delete an object from the array
vector< A > v; (A is the name of class)

Does find accepts the object as its 3rd if not what ways can a follow to delete an object.In fact I want to search the particular attribute(such as id, name) value from the array of objects and then delete that object.

please advice?

Edited by munitjsr2 because: n/a
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Dani AI

Generated

was right about why the compiler vomited template errors: std::find needs a way to test equality for your A objects. There are three practical, modern choices (and a few style fixes in your posted loop that will avoid confusion).

First, simplest: search by attribute with a predicate instead of relying on operator==. With C++11+ you can use std::find_if (or std::remove_if + erase to delete all matches). Example — find one element by id and erase it:

std::vector<A>::iterator it =
    std::find_if(v.begin(), v.end(),
                 [&](const A& a){ return a.getId() == targetId; });

if (it != v.end())
    v.erase(it);

To delete every element that matches a condition, use the erase–remove idiom:

v.erase(std::remove_if(v.begin(), v.end(),
                       [&](const A& a){ return a.getId() == targetId; }),
        v.end());

If you must support older compilers without lambdas, write a small functor with operator() and pass that to find_if or remove_if. Alternatively, defining A::operator== is fine when equality semantics are unambiguous — but for “find by id” a predicate is clearer.

Other practical notes based on the code shown: the loop pushes back then always calls v[0].getData(...) — that means you only ever edit the first element; use v[i] or v.back() after push_back. Prefer std::string over char[], add int getId() const / const std::string& getName() const accessors, and keep I/O code out of the data class (separate concerns). Finally, always check it != v.end() before erasing, be mindful that erase invalidates iterators to removed elements, and consider using a modern compiler with C++11 support to take advantage of lambdas and safer idioms.

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Member Avatar for Mr. K

Did you find any error?

Member Avatar for munitjsr2

Did you find any error?

well a new tab opened when i compiled it.( stl_algo.h opened) and

got many lines of error i don't understand

C:\Dev-Cpp\include\c++\3.4.2\bits\stl_algo.h In function `_RandomAccessIterator std::find(_RandomAccessIterator, _RandomAccessIterator, const _Tp&, std::random_access_iterator_tag) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<A*, std::vector<A, std::allocator<A> > >, _Tp = A]':

314 C:\Dev-Cpp\include\c++\3.4.2\bits\stl_algo.h instantiated from `_InputIterator std::find(_InputIterator, _InputIterator, const _Tp&) [with _InputIterator = __gnu_cxx::__normal_iterator<A*, std::vector<A, std::allocator<A> > >, _Tp = A]'


and many more lines, I dont get it
compiler (DevC++ version )

Edited by munitjsr2 because: n/a
Member Avatar for Insensus

If you look at this page http://www.cplusplus.com/reference/algorithm/find/ you'll see that find() requires the == operator to be defined on your class, and it's not.

Something like this probably:

bool A :: operator ==(const A &t) const
{
	return ((x == t.x) && (strcmp(name, t.name) == 0));
}

On a side note, why did you define putData() as a member-function of A even though it doesn't do anything with the A it's called from?

And why does getData() take an argument which it doesn't use?

Edited by Insensus because: n/a
Member Avatar for munitjsr2

If you look at this page http://www.cplusplus.com/reference/algorithm/find/ you'll see that find() requires the == operator to be defined on your class, and it's not.

Something like this probably:

bool A :: operator ==(const A &t) const
{
	return ((x == t.x) && (strcmp(name, t.name) == 0));
}

On a side note, why did you define putData() as a member-function of A even though it doesn't do anything with the A it's called from?

And why does getData() take an argument which it doesn't use?

Thanks, I got this

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