Why String is returning Junk values - c++

Question

Here I am using Data Structure Queues to change cards places using strings. User picks the top card than put it at last of the deck. The problem is that I need to return updated string to main. What it is returning is junk Values. I also tried to copy the string array and than returning that arraybut didn't work. Can anyone help?
#include<iostream>
#include<string>
using namespace std;
string CommunityChest(string Cards[]){
struct Que{
string cards[6];
int front =0;
int back=-1;
}ComQ;
string temp;
for(int i=0; i<5;i++)
{//Enqueue(Cards)
ComQ.back++;
if(ComQ.back<=5)
{
ComQ.cards[ComQ.back]=Cards[i];
}
else{
cout<<"Overflow";
}
}
//Display
for(int i=ComQ.front; i<=ComQ.back; i++)
{
cout<<ComQ.cards[i]<<endl;
}
//Del()
if(ComQ.front>=0)
{
temp=ComQ.cards[ComQ.front];
ComQ.front++;
}
cout<<endl<<"Pick the top Card"<<endl;
cout<<temp<<endl;
//EnQ the picked card
ComQ.back++;
if(ComQ.back<=5)
{
ComQ.cards[ComQ.back]=temp;
}
else{
cout<<"Overflow";
}
cout<<endl<<"After Inserting top card:"<<endl;
//Display
string newQ1[5];
for (int i=ComQ.front; i<=ComQ.back; i++) //Making an alternate array to copy Comq.cards array data
{
newQ1[i]=ComQ.cards[i];
}
for(int i=0; i<5; i++)
{
return newQ1[i]; //trying to return string array
//cout<< newQ1<<endl;
}
}
int main(){
string cards[5]{ "1 Advance ........",
"2. It is your ...........",
"3. You have won .............",//Cards as strings
"4. From sale of..............",
"5. Pay Hospital............"};
string newQ1=CommunityChest(cards);
for(int i=0; i<5; i++)
cout << newQ1[i] << endl;
return 0;
}

Answer 1

There are some issues with this code as mentioned in the comments, you are trying to do a return in a loop, this may look okay but it's wrong since a return can get you out of the function. But it seems like you want to return an array of strings.
A fix for this function would be like this:
#include <iostream>
std::string* CommunityChest(std::string Cards[]) {
struct Que {
std::string cards[6];
int front = 0;
int back = -1;
} ComQ;
std::string temp;
for (int i = 0; i < 5; i++) { // Enqueue(Cards)
ComQ.back++;
if (ComQ.back <= 5) {
ComQ.cards[ComQ.back] = Cards[i];
}
else {
std::cout << "Overflow";
}
}
// Display
for (int i = ComQ.front; i <= ComQ.back; i++) {
std::cout << ComQ.cards[i] << std::endl;
}
// Del()
if (ComQ.front >= 0) {
temp = ComQ.cards[ComQ.front];
ComQ.front++;
}
std::cout << std::endl
<< "Pick the top Card" << std::endl;
std::cout << temp << std::endl;
// EnQ the picked card
ComQ.back++;
if (ComQ.back <= 5) {
ComQ.cards[ComQ.back] = temp;
}
else {
std::cout << "Overflow";
}
std::cout << std::endl
<< "After Inserting top card:" << std::endl;
// Display
// Creating a dynamic array to store the values
std::string* newQ1 = new std::string[5];
for (int i = ComQ.front, j = 0; i <= ComQ.back && j < 5; i++, j++) {// Making an alternate array to copy Comq.cards array data
newQ1[j] = ComQ.cards[i];
}
return newQ1; // Returning the dynamic array
}
int main()
{
std::string cards[5]{
"1 Advance ........",
"2. It is your ...........",
"3. You have won .............", // Cards as strings
"4. From sale of..............",
"5. Pay Hospital............"
};
std::string* newQ1 = CommunityChest(cards);
for(int i = 0; i < 5; i++) {
std::cout << newQ1[i] << std::endl;
}
delete[] newQ1; // Deleting the array
return 0;
}
The output will be:
1 Advance ........
2. It is your ...........
3. You have won .............
4. From sale of..............
5. Pay Hospital............
Pick the top Card
1 Advance ........
After Inserting top card:
2. It is your ...........
3. You have won .............
4. From sale of..............
5. Pay Hospital............
1 Advance ........
In this fix, I'm returning a dynamically allocated array of strings because a static array will be destroyed once the scope ends, it would be better sometimes to use other ways to allocate memory such as std::unique_ptr<> or std::shared_ptr<>, but I'd suggest you learn how to do it yourself first then use those when needed.
EDIT:
You can also return an std::array<>, I suggest you to read about it as C-Style arrays cannot be returned in you way that you tried and can't be returned without using dynamic allocation, so an std::array<> can be a good replacement over std::string* in this case