How do I add item into the array in C++ with unlimited size? [duplicate]

In python, there's a function call append to add an item into the back of the list. Is there similar function in C++ to add an item into the array? Or is there any other alternative method so that I can add item into an array with undefined size?

#include <iostream>
using namespace std;

int main(){
    int list1[] = {1,2,3,4};
    //a function that add an item at the back of the array;
    cout<<list1[4]<<endl;
    return 0;
}