operator<< and stringstream overloading in c++ [closed] - c++

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Problem:
From overloaded operator<<, cout will only print first bit:``"Hello guys, ", while the stream is multiple shifts << "Hello guys, " << "I can't get here!" << str << "\n"`.
My question is, why I only get the first bit of stream?
Code:
#include <iostream>
#include <sstream>
#include <string>
class Debug {
private:
std::stringstream stream;
public:
std::string str() const{
return stream.str();
}
std::stringstream& operator<<(std::string &s) {
stream << s;
std::cout << s;
return stream;
}
std::stringstream& operator<<(const char s[]) {
stream << s;
std::cout << s;
return stream;
}
};
std::ostream &operator<<(std::ostream &output, const Debug &d) {
output << d.str();
return output;
}
int main() {
Debug debug;
std::string str("Bad input");
debug << "Hello guys, " << "I can't get here!" << str << "\n";
std::cout <<"\n\n"<< debug;
std::cin.get();
return 0;
}

Answer 1

My question is, why I only get the first bit of stream?
as it was mentioned in the comments, any further calls after the 1st one of the Debug::operator<<() overload, will go to the overloaded operator of std::stringstream because you return a reference to that one.
What you probably want is a class that wraps a std::ostream interface like follows:
class Debug {
std::ostream& os_;
public:
Debug(std::ostream& os) : os_(os) {}
template<typename T>
Debug& operator<<(T val) {
// Intercept whatever you want to intercept here ...
os_ << val;
return *this;
}
};
This will ensure that the Debug::operator<<() overload is called repeatedly when the statement
debug << "Hello guys, " << "I can't get here!" << str << "\n";
is going to be executed.
int main() {
Debug debug(std::cout);
std::string str("Bad input");
debug << "Hello guys, " << "I can't get here!" << str << "\n";
return 0;
}
Outputs:
Hello guys, I can't get here!Bad input
See the Live Demo.
To collect the stuff at an inner stream, and just output the contents at a certain point, you can do it as follows:
#include <iostream>
#include <string>
#include <sstream>
class Debug {
std::ostringstream os_;
public:
template<typename T>
Debug& operator<<(T val) {
os_ << val;
return *this;
}
// Overload the operator<< to output the buffered stuff
friend std::ostream& operator<<(std::ostream& os, const Debug& debug) {
os << debug.os_.str();
return os;
}
};
int main() {
Debug debug;
std::string str("Bad input");
debug << "Hello guys, " << "I can't get here!" << str << "\n";
std::cout << debug;
return 0;
}
Another Live Demo.