Words in reverse order, string

[sanasuke15]

Hello I'm trying to right a program that reverses the order or words in strings.
The thing is I don't know how to do this. I only know how to reverse each letter using strrev() and the for loop method like:

 #include <iostream>
#include <cstring>
using namespace std;

int main ()
{
    char str[20];
    cout << "Enter a string: ";
    cin.getline(str, 19);
    int sizestr = strlen(str);
    for(int i=0;i<sizestr+1;sizestr--)
    {
        cout << str[sizestr];
    }
	return 0;
}

But I'm required to reverse the word order something like

Enter a string: Whats up
reversed: up Whats

I need ideas on this. Thanks!!

[Chervil]

A first step might be to identify each individual word in the string. There are many ways to do this, though a stringstream might be the simplest. Then generate a new string by inserting each word (and a separating space if necessary) at the beginning of the new string.
http://www.cplusplus.com/reference/string/string/insert/

Or store all the individual words in an array or vector and loop in reverse through the stored words to build the new string.