Why string is not printed?C++

Question

#include <iostream>

using namespace std;

template<class T>
class Array{
public:
    T U[10];

    friend void DataOut(Array<string>);
    friend void GetData(Array<string>);
};

void DataOut(Array<string> Array1){
    cout << Array1.U[0];
}

void GetData(Array<string> Array1){
    cin >> Array1.U[0];
    cin.clear();
}

int main(){
    Array<string> Arr1;
    GetData(Arr1);
    DataOut(Arr1);
}

I made a class template and created two functions: GetData for entering string and DataOut for printing that string, but after entering string it doesn't print it. What have I done wrong?

Pass by value instead of by reference. As in, what you are doing vs. what you should do. — sweenish, May 14 '21 at 20:40
It might be because you are passing a copy of the variable `Arr1`into `Getdata` rather than a reference to it. — Andrew Truckle, May 14 '21 at 20:41
The answer to that sub question [can be found here](https://stackoverflow.com/questions/388242). — user4581301, May 14 '21 at 20:48

score 1 · Answer 1 · answered May 14 '21 at 20:43

1

I placed comments where I made changes. The main fix is to pass your object by reference, especially to Getdata(). You passed a copy, put data into the copy, and when the function ended, the copy goes away and your original object was never touched.

#include <iostream>

using namespace std;

template <class T>
class Array {
 public:
  T U[10];

  friend void DataOut(
      const Array<string>&);  // CHANGED: Need to take object by reference
  friend void GetData(Array<string>&);  // SAME
};

void DataOut(const Array<string>& Array1) {  // SAME
  cout << Array1.U[0];
}

void Getdata(Array<string>& Array1) {  // SAME
  cin >> Array1.U[0];
  // cin.clear();  // CHANGED: Why?
}

int main() {
  Array<string> Arr1;
  Getdata(Arr1);
  DataOut(Arr1);
}

answered May 14 '21 at 20:43

sweenish

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1

Why? To clear out the data left in the stream of course! Why else would you call a function named `clear`? To clear error flags? – user4581301 May 14 '21 at 20:46
1

@user4581301: Clearing error flags is what it does, if you want to flush the remaining data that would be `ignore` – Ben Voigt May 14 '21 at 20:59
It seems unnecessary here is what I was intending. I know what it does. – sweenish May 15 '21 at 01:52

Why string is not printed?C++

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