Combine input and output streams - c++

Question

I want to combine both input and output stream to the output stream.
I mean, if this is my code:
int num;
string str;
cout << "string: ";
cin >> str;
cout << "num: ";
cin >> num;
cout << "num is " << num << " str is " << str;
And I redirect the input stream to a txt file contains:
hey 1
My output stream will contain:
string: hey
num: 1
num is 1 str i hey
insted of:
string: num: num is 1 str is hey
I don't want to cout each variable in cin after I get my input. I want it to be automatically.

Answer 1

Overload std::istream::operator >> for a wrapper class and do what you like:
// Example program
#include <istream>
#include <string>
#include <vector>
class AutoCinToCoutReader {
public:
inline void write(const std::string& in) { std::cout << in << std::endl; }
};
std::istream& operator >> (std::istream& is, AutoCinToCoutReader& dt)
{
std::string in;
is >> in;
dt.write(in);
return is;
}
void read(const std::string& what, AutoCinToCoutReader& rd) {
std::cout << what << ": ";
std::cin >> rd;
}
int main()
{
AutoCinToCoutReader rd;
std::vector<std::string> fields = { "Test1", "Test2" };
for(const std::string& field : fields) {
read(field, rd);
}
}
Update:
The smallest thing I could offer is:
// Example program
#include <string>
#include <vector>
#include <iostream>
#include <istream>
#include <ostream>
std::istream& operator >> (std::istream& is, std::ostream& os) {
std::string in;
is >> in;
os << in << std::endl;
return is;
}
void read(const std::string& what) {
std::cout << what << ": ";
std::cin >> std::cout;
}
int main()
{
std::vector<std::string> fields = { "Test1", "Test2" };
for(const std::string& field : fields) {
read(field);
}
}
You can not immediately write into cout from cin. In any case, you need to work around it. See the updated operator, directly outputting to cout after storing in cin.