我如何重载<<操作符以在C ++中打印数组的内容？

Question

This is my function, and it is crashing when I run the program. I am trying to print out the contents of a char array. How do I overload this operator to print out the contents of an array without my program crashing?

ostream& operator<< (ostream& out, MyString& obj){

  //print out mystring contents

  int i = 0;
  while(i < obj.size)
  {
      out << obj.data[i];
      i++;
  }
}

Here are my data members:

int size;
int capacity;
char *data;

I made the following modifications, but it still crashes:

int i = 0;
    while(obj.data[i] != '\0')
    {
        out << obj.data[i];
        i++;
    }

    return out;

Answer 1

You need to return something if you declared your function as such:

return out;

Without it, you have Undefined Behavior, one possible outcome of which is program crash.

Please, as you are learning set your compiler to treat warnings as errors.

Just a little tip, as NathanOliver said to you, ostreams are already setup to print character arrays as long as they are null terminated, so as long as obj.data is a null-terminated string, you can do:

ostream& operator<< (ostream& out, MyString& obj){

  //print out mystring contents
  if (obj.data != nullptr) // you might need this test, you might not, depending on the internal logic of MyString
    out << obj.data;

  return out;
}

Answer 2

You want to return your ostream object:

ostream& operator<< (ostream& out, MyString& obj) {
    for (size_t i = 0; i < obj.size; ++i) {
        out << obj.data[i] << " ";
    }
    return out;
}