如何使用向量参数编写递归 function？

Question

I have a function that takes a vector as a parameter, scan this vector and generates a random word. It's expected from me that the generated words' letters are different from each other. So, I want to check it with a simple if-else condition inside the same function. If all letters are different, function returns this word. If not, I need to use the same function which I am already inside while using conditions. But first parameter that I used in the main function doesn't work when I attempt to use it for the second time. Here the generateaRandomWord(vector a) function:

vector<string> currentVector;
string generateaRandomWord(vector<string> a) {
    currentVector = a;
    string randomWord;
    int randomNumber = rand() % currentVector.size();
    randomWord = currentVector.at(randomNumber);
    
    if (hasUniqueChars(randomWord)) {
        return randomWord;
    }
    else {
        generateaRandomWord(currentVector);
    }
    
}

I thought that it is a good idea to keep a vector (currentVector) outside of the function. So, for the first time I use the function this vector will be defined and I will be able to use it if using recursion is necessary. But that didn't work either.

Answer 1

The main problem you have is that your recursive case doesn't return anything -- it throws away the returned value from the recursive call, then falls off the end of the function (returning garbage -- undefined behvaior). You need to actually return the value returned by the recursive call:

        return generateaRandomWord(currentVector);