Vectors And Merging - c++

Question

For this vectors and merging assignment, we are supposed to read in user inputted strings and sort them alphabetically. I got the first two parts, but when I am putting the sorted elements in the new vector, it says that my new vector is out of range. Does anyone know how to fix this?
#include <iostream>
#include <vector>
using namespace std;
int main() {
vector<string> que1;
vector<string> que2;
vector<string> que_merge;
string firstName;
string secondName;
int counterq1 = 0;
int counterq2 = 0;
cout << "Enter queues: " << endl;
bool check = true;
while(check) {
cin >> firstName;
if (firstName == "ENDQ"){
check = false;
}
else{
que1.push_back(firstName);
counterq1++;
check = true;
}
}
// que1.resize(counterq1);
bool check2 = true;
while (check2) {
cin >> secondName;
if (secondName == "ENDQ") {
check2 = false;
} else {
que2.push_back(secondName);
counterq2++;
}
}
// que2.resize(counterq2);
cout << "que1: " << counterq1 << endl;
for (int i = 0; i < que1.size(); i++) {
cout << que1.at(i) << endl;
}
cout << endl;
cout << "que2: " << counterq2 << endl;
for (int j = 0; j < que2.size(); j++) {
cout << que2.at(j) << endl;
}
cout << endl;
cout << "que_merge: " << counterq1 + counterq2 << endl;
int i = 0;
int k = 0;
int j = 0;
while (1){
if (i >= counterq1 || j >= counterq2){
break;
}
if(que1.at(i) < que2.at(j)){
que_merge.push_back(que1.at(i));
i++;
}
else{
que_merge.push_back(que2.at(j));
j++;
}
k++;
}
if (que1.empty()){
for (int m = j; m < counterq2; m++){
que_merge.push_back(que2.at(m));
}
} else {
for (int l = i; l < counterq1; ++l) {
que_merge.push_back(que1.at(l));
}
}
for (int l = 0; l < (counterq1+counterq2); l++) {
cout << que_merge.at(l) << endl;
}
return 0;
}

Answer 1

I think your problem is that these lines:
if (que1.empty()){
for (int m = j; m < counterq2; m++){
que_merge.push_back(que2.at(m));
}
} else {
for (int l = i; l < counterq1; ++l) {
que_merge.push_back(que1.at(l));
}
}
doesn't do what you expect.
As far as I can see, your idea is to merge the remaining element from either que1 or que2.
However, that is not what you get from this code as the elements in que1 and que2 is never erased. In other words - the check for an empty queue is rather meaningless and you can't be sure that all elements are added to que_merge
So when you do:
for (int l = 0; l < (counterq1+counterq2); l++) {
cout << que_merge.at(l) << endl;
}
you may read beyond the number of elements in que_merge
Tip:
Don't count the number of elements your self. Use size() (like que_merge.size()) instead. For instance:
for (int l = 0; l < que_merge.size(); l++) {
cout << que_merge.at(l) << endl;
}
or a range based loop like:
for (const auto& s : que_merge) {
cout << s << endl;
}

Answer 2

#include <algorithm>
Use std::merge and std::sort, not necessarily in that order.
If the assignment says you can't do it the C++ way, that you have to write it all out, you can do it the engineer's way: Find an example that works, and crib it.
There are two possible implementations of std::merge on this page: All about C++ merge