constructing-output-stream-objects.md

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Learn more about: Constructing Output Stream Objects	Constructing Output Stream Objects	11/04/2016	output stream objects	93c8eab6-610c-4f48-b76d-1d960cac7641

Constructing Output Stream Objects

If you use only the predefined cout, cerr, or clog objects, you do not need to construct an output stream. You must use constructors for:

• Output File Stream Constructors

• Output String Stream Constructors

Output File Stream Constructors

You can construct an output file stream in one of two ways:

• Use the default constructor, and then call the open member function.

  ofstream myFile; // Static or on the stack
  myFile.open("filename");
  
  ofstream* pmyFile = new ofstream; // On the heap
  pmyFile->open("filename");

• Specify a filename and mode flags in the constructor call.

  ofstream myFile("filename", ios_base::out);

Output String Stream Constructors

To construct an output string stream, you can use ostringstream in the following way:

using namespace std;
// ...
ostringstream myString;
myString << "this is a test" << ends;

string sp = myString.str(); // Obtain string
cout << sp << endl;

The ends "manipulator" adds the necessary terminating null character to the string.

See also

Output Streams