23.2.1.cpp

#include<iostream>
#include<stack>
#include <string>
using namespace std;



void reverseSentence(string s){
    stack<string> st;

    for(int i=0; i<s.length(); i++){
        string word="";
        while(s[i]!=' '&&i<s.length()){
            word+=s[i];
            i++;
        }
        st.push(word);
    }   

    while(!st.empty()){
        cout<<st.top()<<" ";
        st.pop();

    }
    cout<<endl;
}
int main(){
    string s = "Hey, how are you doing?";
    reverseSentence(s);
}