Thread: StringStream

Ah, after I read carefully about stringstream. I have some code below:

Code:

int main(){
//string to Int
/* ******************************************** */
    stringstream ss;
    printf("FIRST TEST\n");
    string strNum;
    cin>>strNum;
    ss<<strNum;
    int a;
    ss>>a;
    a=a+1;
    cout<<a<<endl;  //NO PROBLEM HERE


    //int to String
/* ******************************************* */
    printf("SECOND TEST\n");
    int num;
    cin>>num;
    ss<<num;
    string str;
    ss>>str;
    str=str+" IS A NUMBER";
    cout<<str<<endl;   //PROBLEM: it just print "IS A NUMBER"


 /* ****************************************** */
    printf("THIRD TEST\n");
    stringstream ss_2;  string str_2;
    cin>>num;
    ss_2<<num;
    ss_2>>str_2;
    str_2=str_2+" IS A NUMBER";
    cout<<str_2<<endl;   //NORMAL AGAIN: it will print: "<num> IS A NUMBER"
    /* ****************** */
    return 0;
}

//Note: PROBLEM mean I don't want like that, not something's wrong

Uhm, in above code, at second test, if I use ss stringstream again, ss>>str will not put flow in ss into str. and the problem will be solved if I use another variable(example: ss_2). So, who can explain for me please

thanks

yes, I have tried it, But It meets same problem with me . this is my code, building from your code:

Code:

int main(){
int num;
    stringstream ss;
    string output;
    cout<<"Enter a number:";
    cin>>num;
    ss<<num;
    ss>>output;
    output+=" is a number";
    cout<<output<<endl;



    /* ********************** */
    cout<<"Enter a number again:";
    cin>>num;
    ss<<num;
    ss>>output;
    output+=" is a number";
    return(0);
}

So, who can explain for me please

I would but I cannot understand your post.

Just FYI, template functions can make arbitrary conversions fairly trivial:

Code:

#include <sstream>
#include <cctype>
#include <typeinfo>

template <typename Dst, typename Src>
bool iocpy(Dst& dst, const Src& src)
{
	bool success = true;
	std::stringstream io;
	if(!(io << src) || !(io >> dst))
		success = false;
	else
	{
		char ch;
		while(io.get(ch))
			if(!std::isspace(ch))
				success = false;
	}
	if(!success)
		dst = Dst();
	return success;
}

template <typename Dst, typename Src>
Dst iocpy(const Src& src)
{
	Dst dst;
	if(!iocpy(dst, src))
		throw std::bad_cast();
	return dst;
}

#include <iostream>

int main(int argc, char** argv)
{
	using namespace std;
	int sum = 0;
	for(int a = 1; a < argc; ++a)
	{
		try
		{
			sum += iocpy<int>(argv[a]);
		}
		catch(bad_cast&)
		{	
			cout << "Sorry, '" << argv[a] << "' is not an integer!" << endl;
		}			
	}	
	cout << "Sum: " << sum << endl;
}

@grumpy: your answer maybe useless to me, until I read my code again, and, :"> I haven't printed <string>output to monitor,yet.
And after that, I see that ss.clear() have solve my question completely.(at post 1 and post 3, too)

Again, I'm sorry sorry so much for my fault