#include<vector>
vector<string> vect;
vector<string>::iterator ab;

#include "abc.h"

    vect.push_back("a");
    vect.push_back("b");
    for(ab = vect.begin(); ab != vect.end(); ab++)
    {
    if(*ab == "b")
    {
    FIle *file->fun();
    }

#include "abc.h"

    File::file()
    {
    vect.insert(1, "Something");
    }

"class std::_Vector_iterator<class std::_Vector_val<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::allocator<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > > > > testCase" (?testCase@@3V?$_Vector_iterator@V?$_Vector_val@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@V?$allocator@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@2@@std@@@std@@A) already defined in abc.obj
1>GTestThread.obj : error LNK2005: "class std::vector<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::allocator<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > > > vect" (?vect@@3V?$vector@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@V?$allocator@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@2@@std@@A) already defined in abc.obj
1>D:/ fatal error LNK1169: one or more multiply defined symbols found

vector<string> vect;
vector<string>::iterator ab;

//abc.h
extern vector<string> vect;
extern vector<string>::iterator ab;

//abc.c
#include "abc.h"
vector<string> vect;
vector<string>::iterator ab;

extern vector <string> vect;