c++ - Allways repeating random pick -

so have code here. objective create multiple choice quiz questions coming text file , picked randomly displayed. able multiple choice, problem when generates, question pick , displayed being displayed again. choices coming answers on text file, problem choices being displayed repeatedly in question.

so want know how not display pick question again, , how choices not being displayed repeatedly.

example output

1. month celebrate christmas? a.december b.december c.january d.december    //randomizes questionlist vector random_shuffle(questionlist.begin(), questionlist.end()); //goes through every test question  for(int = 0; < questionlist.size(); i++){     vector <test> randomanswer;          //puts correct answer first     randomanswer.push_back(questionlist[i]);     //then randomly gets 3 other answers questionlist     while(randomanswer.size() < 4)     {     int random = rand();     if(random != i){         randomanswer.push_back(questionlist[rand() % (questionlist.size() - 1)]);     }                 //shuffle answers     random_shuffle(randomanswer.begin(), randomanswer.end());     //print question     cout << questionlist[i].getquestion() << ":" << endl;     //initialize first choice character 'a'     char ch = 'a';     //prints shuffled answers     for(int j = 0; j < randomanswer.size(); j++)     {         cout << ch << ") " << randomanswer[j].getanswer() << endl;         //increment 'a' can print 'b' , forth         ++ch;     }     //get users response     cout << "\nyour answer: ";     cin  >> response;     //bool data type determine if correct answer found     bool iscorrect = false;     switch(toupper(response))      {     case 'a':         if(randomanswer[0].getanswer()==questionlist[i].getanswer())         iscorrect = true;         break;     case 'b':         if(randomanswer[1].getanswer()==questionlist[i].getanswer())         iscorrect = true;         break;     case 'c':         if(randomanswer[2].getanswer()==questionlist[i].getanswer())         iscorrect = true;         break;     case 'd':         if(randomanswer[3].getanswer()==questionlist[i].getanswer())         iscorrect = true;         break;     default:         cout << "\nincorrect input.\n";     }     //if answer found print "correct" else "wrong"     if(iscorrect)     {         cout << "\nyou got answer correct!\n";     }     else     {         cout << "\nyou got answer wrong!\n"         << "correct answer " << questionlist[i].getanswer() <<          endl; 

your approach incorrect, insert correct answer in list , randomly pick 3 answers. visual example (1 correct):

1 2 3 4 insert 1 randomanswer randomly pick 3 numbers , insert them randomanswer: ex (2, 1, 3) 

the correct approach take 4 answers , shuffle them. psuedocode

swap(questionlist[i], *(questionlist.end() - 1)); insert questionlist[i] shuffle questionlist.begin() - questionlist.end() - 2 , randomly pick 3