Find common strings in two lists

Solution

#include <iostream>

#include <list>

#include <iterator>

#include <algorithm>

#include <string>

using namespace std;

void find_comm_strings(list<string>& output, list<string>& listA, list<string>& listB)

{

listA.sort();

listB.sort();

list<string>::const_iterator citA = listA.begin();

list<string>::const_iterator citB = listB.begin();

while(citA != listA.end() && citB != listB.end()){

int eq = (*citA).compare(*citB);

if(eq == 0){

output.push_back(*citA);

citA ++;

citB ++;

}

else if (eq > 0){

citB ++;

}

else{

citA ++;

}

}

}

int main(int argc, char* argv[])

{

list<string> listA;

list<string> listB;

list<string> output;

cout << "list A:" << endl;

listA.push_back("dog");

listA.push_back("bird");

listA.push_back("elephant");

listA.push_back("dog");

listA.push_back("dog");

listA.push_back("cat");

copy(listA.begin(), listA.end(), ostream_iterator<string>(cout, ","));

cout << endl;

cout << "list B:" << endl;

listB.push_back("cat");

listB.push_back("dog");

listB.push_back("dog");

listB.push_back("cat");

listB.push_back("cat");

listB.push_back("fish");

copy(listB.begin(), listB.end(), ostream_iterator<string>(cout, ","));

cout << endl;

find_comm_strings(output, listA, listB);

cout << "common strings" << endl;

copy(output.begin(), output.end(), ostream_iterator<string>(cout, ","));

cout << endl;

return 0;

}

Output

list A:

dog,bird,elephant,dog,dog,cat,

list B:

cat,dog,dog,cat,cat,fish,

common strings

cat,dog,dog,

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