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Input and output streams
The tendency of reading and writing data in the C++ programming language is
controlled by the input and output streams. Input and output streams enable a user to
interact with the program by displaying output on the screen and getting the user’s Chapter Four: Object oriented programming with C++
input through the keyboard. Input stream, as shown in Figure 4.26, uses extraction
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operator (>>) to read data from the source/ keyboard to the program. Output stream,
as shown in Figure 4.27, uses insertion operator (<<) to display a program to the
screen/destination. The object of the output stream required to display data is called
“cout” while “cin” is used by the input stream to accept or read data. The objects
“cout” and “cin” are declared within the header file “iostream.”

Reading data from the source
Source Program
Figure 4.26: Input stream

Displaying data to destination/screen
Program Destination
Figure 4.27: Output stream

Note: The insertion and extraction operators can be used more than once in one
stream of data. This signifies that, you can use more than one insertion
operator to display different data using one output stream. You can also use
more than one extraction operators to request more than one data from the

user.
For example: cout<< “Ashura is”<< age<< “years old”<<endl;
cin>>firstNumber>>secondNumber;

The input stream “cin” will process the data entered when the user presses the
RETURN key. The weakness of input stream “cin” is that it cannot hold blank space
characters. The function “getline” can be used instead of “cin” to solve this problem.

The following Program Example 4.12 demonstrates the uses of “cin” and “cout”
commands in a C++ program. The output is shown in Figure 4.28.

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Student’s Book Form Five

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