C++ String reserve()

str.reserve(l);

#include<iostream>
using namespace std;
int main()
{
    string s="Computer Science Technology";
    cout<<?Capacity is :?<<s.capacity()<<'\n';
            s.reserve(33);
            cout<<?Now,capacity is :?<<s.capacity();
    return 0;
}

Capacity is 27
Now,capacity is : 54