Error when calling void function with <set> operator - c++

Question

I am trying to pass a string and and an empty set into my function. Then I would like to call the function in my main and print all of the elements in the set.
This is my function code:
#include<iostream>
using std::cout; using std::endl;
#include<algorithm>
using std::set_union; using std::copy;
#include<iterator>
using std::inserter; using std::ostream_iterator;
#include<string>
using std::string;
#include<set>
using std::set;
void removing(const string &word, set<string> &result) {
string del_word = word;
char erased_l;
for(int i = 0; i < del_word.length(); i++) {
erased_l = word[i];
del_word.erase(0, 1);
del_word = erased_l + del_word;
}
}
Below is my main code where I call the function:
int main (){
set<string> jump = {};
set<string> del = removing("axiom", jump);
for (string ele:del) {
cout << ele << endl;
}
}
I get the following error:
No viable conversion from 'void' to 'set<std::__1::string>' (aka 'set<basic_string<char, char_traits<char>, allocator<char> > >')
The error is in line 16:
set<string> del = removing("axiom", jump);
My code is trying to accomplish:
If I pass in axiom, then I would like my string set to have {xiom, aiom, axom, axim, axio}. So remove first letter, keep rest of the word. Then remove second letter, keep rest of the word, etc...

Answer 1

Primary issues include:
The return value of a void function can't be assigned to a set, hence your compiler error. Your design is to pass a reference to an empty result set into the removing function and have it populated with the result data, so you can remove the assignment here.
Nothing is added to your result inside your removing function, so it starts empty and ends empty after the function call.
Here's a working version:
void removing(const string &word, set<string> &result) {
for (int i = 0; i < word.length(); i++) {
result.insert(word.substr(0, i) + word.substr(i + 1, word.length()));
}
}
int main () {
set<string> jump = {};
removing("axiom", jump);
for (string ele : jump) {
cout << ele << endl;
}
}
Output:
aiom
axim
axio
axom
xiom
Having said that, it's not clear to me why result should be a parameter to the function. If you're only planning on using it to store this particular result, this design seems much cleaner from the perspective of the caller:
set<string> removing(const string &word) {
set<string> result;
for (int i = 0; i < word.length(); i++) {
result.insert(word.substr(0, i) + word.substr(i + 1, word.length()));
}
return result;
}
int main () {
set<string> jump = removing("axiom");
for (string ele : jump) {
cout << ele << endl;
}
}
Try it!