function that push_back value to vector in c++

Question

I am newbie in c++. I wanna create function that push_back value to vector.

#include <vector>
#include <iostream>
using namespace std;
void pushVector ( vector <int> v, int value){
v.push_back(value);
}
int main(){
vector <int> intVector;
pushVector (intVector, 17);
cout << intVector.empty(); // 1
}

As you see, my function don't push_back value in vector. Where is my mistake?

• user1551592: vector<int>& v job done.
• n. m. could be an AI: "Pass by value" vs "pass by reference", look it up.
• jrok: Your mistake is trying to wrap push_back in the first place. Why do you do that?
• Orange Fox: @jrok I do not understand your question :'(

Answer 1

you need to pass the vector to the function by reference. The way you wrote the function, it makes a copy of the vector inside its body, and the vector remains unchanged outside of the function.

#include <vector>
#include <iostream>
void pushVector ( vector <int>& v, int value){
v.push_back(value);
}
int main(){
vector <int> intVector;
pushVector (intVector, 17);
cout << intVector.empty() // 1
}

here is a concise explanation of the issue.

• Orange Fox: Ty for answer. Where can i find information about using this "&" symbol in c++ ?
• WhozCraig: @OrangeFox in literally any C++ book in-print since the language was invented. See this list for suggestions