Returning a vector from a function in order to print the contents - c++

Question

My program has a function named 'WordLadder' that uses BFS to make a path from one word in a dictionary to another. I was given a starter code that prints the number of nodes in the path, but I want to print the path itself. Currently, I have appended the words to a vector as they enter a queue but I am not able to return the vector as part of my 'WordLadder' function in order to print it in the main program.
I just want the program to print a path based on the two words I picked, i.e. "TOON - POON - POIN - POIE - PLIE - PLEE - PLEA", if the start word is "TOON" in the dictionary and the target word is "PLEA" in the dictionary.
I tried to declare the vector outside of the function and print it in main with this code, but I was unsuccessful.
void print(std::vector < int >
const & transformation) {
std::cout << "The vector elements are : ";
for (int i = 0; i < transformation.size(); i++)
std::cout << transformation.at(i) << ' ';
}
I have attempted to return the vector inside of the function, but I receive this error
error: no viable conversion
from returned value of type
'vector<std::__cxx11::string>' (aka
'vector<basic_string<char> >') to
function return type 'int'
return transformation;
Here is my code. Any help would be appreciated, as I am new to C++.
// To check if strings differ by exactly one character
bool nextWord(string & a, string & b) {
int count = 0; // counts how many differences there
int n = a.length();
// Iterator that loops through all characters and returns false if there is more than one different letter
for (int i = 0; i < n; i++) {
if (a[i] != b[i]) {
count++;
}
if (count > 1) {
return false;
}
}
return count == 1 ? true : false;
}
// A queue item to store the words
struct QItem {
string word;
};
// Returns length of shortest chain to reach 'target' from 'start' using minimum number of adjacent moves. D is dictionary
int wordLadder(string & start, string & target, set < string > & ew) {
//Create vector to store path in a
vector < string > transformation;
// Create a queue for BFS and insert 'start' as source vertex
queue < QItem > Q;
QItem item = {
start
};
Q.push(item);
// While queue is not empty
while (!Q.empty()) {
// Take the front word
QItem curr = Q.front();
transformation.push_back(Q.front().word);
Q.pop();
// Go through all words of dictionary
for (set < string > ::iterator it = ew.begin(); it != ew.end(); it++) {
// Proccess the next word according to BFS
string temp = * it;
if (nextWord(curr.word, temp)) {
// Add this word to queue from the dictionary
item.word = temp;
Q.push(item);
// Pop from dictionary so that this word is not repeated
ew.erase(temp);
// If we reached target
if (temp == target) {
return trasformation;
}
}
}
}
return 0;
}
// Driver program
int main() {
string start;
string target;
// make dictionary
std::ifstream file("english-words.txt");
set < string > ew;
copy(istream_iterator < string > (file),
istream_iterator < string > (),
inserter(ew, ew.end()));
cout << endl;
cout << "Enter Start Word" << endl;
cin >> start;
cout << "Enter Target Word" << endl;
cin >> target;
cout << wordLadder(start, target, ew);
return 0;
}

Answer 1

There are multiple problems.
You were on the right track when you said "I tried to declare the vector outside of the function and print it in main..."
So, change wordLadder to take the vector by reference.
int wordLadder(vector<string> &transformation, string & start, string & target, set < string > & ew)
Then declare it in main and pass it to wordLadder
vector<string> t;
wordLadder(t, start, target, ew);
print(t);
You will have to also change print to take a vector of the right type, ie. string and not int
void print(std::vector < string > &transformation)