C++ stream insertion operator overloading
In C++, the stream insertion operator (<<) is an operator used to output data into a stream, and the stream insertion operator can be overloaded so that programmers can customize the way to output objects.
The general form of an overloaded stream insertion operator is as follows:
where, T is the custom type to be output, os is an output stream object of type std::ostream, and obj is the object of the custom type to be output.
The return value of the overloaded function is a reference of type std::ostream, representing the output stream object.
When overloading stream insertion operators, readers need to pay attention to the following points:
1. The overloaded function must be a friend function of the class or a global function.
2. The first parameter of the overloaded function must be a reference of type std::ostream.
3. The second parameter of the overloaded function must be a constant reference of the custom type to be output.
4. The overloaded function must return a reference of type std::ostream.
The following is the stream insertion operator overloading demo I wrote:
In the above demo, I defined a class named MyObject, and overloaded the stream insertion operator << in it.
The first parameter of the overloaded function is a reference of type std::ostream, representing the output stream object;
The second parameter is a reference of type const MyObject, representing the object to be output.
In the overloaded function, I insert a string into the output stream object os, which contains the value of the MyObject object, and finally return the output stream object os.
In the main function, I create a MyObject object obj and use the cout stream to output it to the standard output stream.
Compile and run the above demo results:
