how to find items that occur more than once in a vector

[Alfanumeric]

I was trying to write a program for a vector which usually gives a list of value that will be going to occur more than once in an individual element. Code:

std::vector<int> v2;
vec2[0]=6; vec2[1]=6;here 6 is coming twice. I want to ask if if I make a double loop 
std::vector<int> oc;
{ for (k=0; k<v2.size(); k++) {
   for (l=0; l<v2.size(); l++) {
      if(v2[k] == v2[l]){
         oc.push_back(v2[k]);
      } the output will be 
oc[0]=6;
oc[1]=6;
oc[2]=6;
oc[3]=6;

I had got the value which had being repeated but I want the unique list. I there any way to do so.

[Villiers]

If you are not willing to store the duplicate then you must use std::set which act as a container and will only store the value which is unique. I’m not confirmed but there is an library function which usually gives the value which will going to occur once in an particular vector or there might be a function which will going to take only those element which come twice and that function will sort it and returned only those value which is unique.

[Ronchi]

you can try this hopefully this will going to help you, below is the code:

for (k=0; k<v2.size(); k++) {
   for (l=0; l<v2.size(); l++) {
      if(k != l && v2[k] == v2[l]){ // this will going to remove the element and keep the unique element.
       z = 0;
         for (x=0; x<oc.size(); x++) {
            if(oc[x] == v2[k]){ z++; }
         }
         if(z == 0) { oc.push_back(v2[k]); }

this will surely help you a bit.

[Menominee]

Searching and processing the element which is duplicated is really a big task in the programming. It’s really thought is c programming but usually c++ provide a algorithm to do so you just need to ass the element in the map<entry, int> after that count will come. It will going to compile your program and then ass the build in map with it and after that it will going the count the items that it had come up with. It is necessary to use map in your program.

[Author]

You can simply do this by making use of map operator in your program. I had made the code simple as the value count will be zero at time when it had being initialized.

#include <vector>
#include <map>
int main()
{
    std::vector<int> v3;
    std::map<int, int> CountMap;
    for (auto qw = v3.begin(); qw != v3.end(); ++qw)
        CountMap[*qw]++;
 for (auto qw = CountMap;begin(); qw != CountMap.end(); ++qw)
        if (qw->second > 1)
            cout << "Duplicate " << qw->first << end;
}

[Jacques25]

Well it is not related to this. I’m looking for the program which is used for bitset which will go to tell the number of instances had being created. The data structure is not much large it might be between 0 and 5 which is usually stored in an array. I’m just searching it just to get some knowledge about it. I think so I should but the data in the bitset first where I can able to read the data then enter the data in the different vector. I think so that there is nothing difference in between the map and bitwise according to their algorithm.