Question

As you all know there are libraries using streams such as iostream and fstream.

My question is:

• Why streams? Why didn’t they stick with functions similar to print, fgets and so on (for example)?

They require their own operators << and >> but all they do could be implemented in simple functions like above, also the function

printf("Hello World!");

is a lot more readable and logical to me than

cout << "Hello World";

I also think that all of those string abstractions in C++ all compile down to (less efficient) standard function calls in binary.

Answer 1

Streams have better type safety.

For instance printf("%s", a); can go horribly wrong if a is an integer. cout << a; doesn’t have this problem.

Another issue is that streams better conform to Object Oriented design methodologies.

For instance you have a simple application that writes some output and then you want the output to go to a file instead of to the console. With C calls you’ll have to replace all of the calls to printf to calls to fprintf and take care to maintain the FILE* along the way. With streams you just change the concrete class of the stream you’re using and that’s it, most of the code remains the same like so:

void doSomething(ostream& output)
{
   output << "this and that" << a;
}

doSomething(cout);
doSomething(ofstream("c:\file.txt"));