fatal error: no member named 'find' in 'std::vector >'

Question

Can someone tell why am I getting this error

fatal error: no member named 'find' in 'std::vector<int, std::allocator<int> >'
         if(people.find(people.begin(),people.end(),x)!=people.end())

#include<iostream>
#include<vector>
#define REP(i,a,b) for(int i=a ; i<b ; i++)
using namespace std;
int main(){
    int n,m;
    cin >> n >> m;
    vector<vector<int>> friends;
    vector<int> people;
    vector<int> cost_of_person;
    REP(i,0,n){
        cin >> cost_of_person[i];
        people.push_back(i+1);
    }
    REP(i,0,m){
        int x,y;
        cin >> x >> y;
        if(people.find(people.begin(),people.end(),x)!=people.end()) // error here
            people.erase(x);
        if(people.find(people.begin(),people.end(),y)!=people.end())
            people.erase(y);
        bool inserted = false;
        REP(j,0,friends.size())
        .
        .
        .
        .


    return 0;
}

Well, that's because [`std::vector`](https://en.cppreference.com/w/cpp/container/vector) class doesn't have any member function called `find()`. — Yksisarvinen, May 19 '20 at 15:16
Does this answer your question? [Erasing elements from a vector](https://stackoverflow.com/questions/347441/erasing-elements-from-a-vector) — Yksisarvinen, May 19 '20 at 15:17
Generally, you can also use ```std::find``` in conjunction with a vector, http://www.cplusplus.com/reference/algorithm/find/ — ctenar, May 19 '20 at 15:19
All containers in the std only have the absolute minimum of member functions that are required to control their contents. Everything else is done with free functions, that provide a container independent interface using iterators. — t.niese, May 19 '20 at 15:25

Remy Lebeau · Answer 1 · 2020-05-19T17:25:38.247

std::vector does not have a find() member method. You need to use the std::find() algorithm instead:

#include <algorithm>

if (std::find(people.begin(), people.end(), x) != people.end())
    people.erase(x);
if (std::find(people.begin(), people.end(), y) != people.end())
    people.erase(y);

However, you will then get a new error, because std::vector::erase() does not take an element value as input, it takes an iterator instead. So you need to fix that, too:

vector<int>::iterator iter = std::find(people.begin(), people.end(), x);
if (iter != people.end())
    people.erase(iter);
iter = std::find(people.begin(), people.end(), y);
if (iter != people.end())
    people.erase(iter);

Another problem I see with your code is you are not adding elements to your cost_of_person vector correctly, corrupting memory. You have two choices to fix that:

resize cost_of_person before entering the loop:

vector<int> cost_of_person(n);
REP(i,0,n){
    ...
}

Or

vector<int> cost_of_person;
cost_of_person.resize(n);
REP(i,0,n){
    ...
}

use cost_of_person.push_back() inside the loop:

vector<int> cost_of_person;
REP(i,0,n){
    int cost;
    cin >> cost;
    cost_of_person.push_back(cost);
    people.push_back(i+1);
}

score 0 · Answer 2 · answered May 19 '20 at 15:25

The problem is here:

if(people.find(people.begin(),people.end(),x)!=people.end())

You are using member function of object people named find. However, it turns out that people is defined as:

vector<int> people;

It is a vector. And that type doesn't have a member function named find. Because you call a non-existing member function, the program is ill-formed. As a consequence, you get a diagnostic message from the compiler:

fatal error: no member named 'find' in 'std::vector >'

To fix it, don't call functions that don't exist.

fatal error: no member named 'find' in 'std::vector >'

2 Answers2