How can I use a string stream to do multiple conversions?

[Loctan]

I want to use a string stream to convert an int to a string, then a string to an int use the same stringstream. If I declare two like this, it works fine:

#include <iostream>
#include <string>
#include <sstream>


int main()
{
    const int iNum = 56;
    std::string sNum;
    const std::string str("78");
    int num;
    std::stringstream ss;
    
    //stuff int into the stream
    ss<<iNum;
    
    //release the stream as an string
    sNum = ss.str();
    
    //print both results
    
    std::cout<<"iNum: "<<iNum<<std::endl;
    std::cout<<"sNum: "<<sNum<<std::endl;
    
    std::stringstream ss1;
    ss1<<str;
    ss1>>num;
    
    std::cout<<"str: "<<str<<std::endl;
    std::cout<<"num: "<<num<<std::endl;    
    std::cin.ignore();
    std::cin.get();    
}

Here is the output:

iNum: 56
sNum: 56
str: 78
num: 78

This is exactly what I expect. But what if when I am writing the program I don't want to have to declare multiple string streams? Basically this is what I want to do:

1. declare a string stream object
2. stuff an integer in it
3. call the str() function on the object to get the int value as a string
4. *here is the confusing part. Now i need to clear this stream. I don't know how without declaring a new string stream object*
5. Then I want to stuff a string into the cleared string stream object
6. Now I want to put the stream into an int and print the value.

Below is my attempt at this:

#include <iostream>
#include <string>
#include <sstream>



int main()
{
    const int iNum = 56;
    std::string sNum;
    const std::string str("78");
    int num;
    std::stringstream ss;
    
    //stuff int into the stream
    ss<<iNum;
    
    //releaase the stream as an string
    sNum = ss.str();
    
    //print both results
    
    std::cout<<"iNum: "<<iNum<<std::endl;
    std::cout<<"sNum: "<<sNum<<std::endl;

    /**********Need to somehow clear the stream here*****/   

    ss<<str;
    ss>>num;
    
    std::cout<<"str: "<<str<<std::endl;
    std::cout<<"num: "<<num<<std::endl;    
    std::cin.ignore();
    std::cin.get();
      
}

Here is my output:

iNum: 56
sNum: 56
str: 78
num: 5678

Obviously my stream isn't getting cleared. Inthe above point where I need to clear the stream I have tried everything on this page that looks applicable: http://www.cppreference.com/cppio/index.html

1. ss.clear();
2. ss.flush();
3. ss.ignore(std::numeric_limits<std::streamsize>::max(), '\n');

I just don't know what to put there. Any ideas? Thanks.

[Cactus_Hugger]

Never actually tried to do this myself, but ss.str(""); seems to work. See this documentation.

[Loctan]

Sweet. Thank you very much.

[Daved]

Or simpler would be to just go straight to ss.str(str);

If you are doing input, you might also need to call clear() to clear any error bits that are set, like eofbit or failbit.