1. Data Streams

2. Extraction Extraction Operator [ cin>> num1]
Extracts formatted data from an input stream
Data in the same format as the data type that it is being extracted to.
Ex. extracting to an integer will attempt to take whatever is in the stream and conform it to the integer data type.
Ignores whitespace

3. Extraction
Questions

4. Extraction Questions How do we extract whitespace?
What happens if the data in the stream doesn’t match the data type?
What if there is junk in the stream and we need to get rid of it?

5. Extraction How do we extract whitespace? Unformatted Extraction
Character Extraction
The get function – extracts a single character from the stream.
String Extraction
The getline function – extracts a string from the stream.
It needs a delimiter (or just use the default)

6. Extraction
What happens if the data in the stream doesn’t match the data type?
Stream failure!
No additional information can be extracted from the stream
The status of a stream can be checked using two functions.
The good function
The fail function
The stream can be reset back to the good state by using the clear function.

7. Extraction
What if there is junk in the stream and we need to get rid of it?
We can clear the stream of all the data in the stream (up to a certain number of characters or up to a delimiter) by using the ignore function.

8. Insertion Insertion Operator [ cout << num;]
Inserts data into an output stream
We can immediately send all the data in the stream to the output device using the flush function.

9. Keyboard
Monitor
Program.exe
cin
cout
Stream Diagram 1.0

10. Streams
Questions

11. Streams
Questions
What other devices can we connect to a program using a stream?
How do we write to or read from a file?

12. Stream Diagram 2.0 Program.exe Keyboard Monitor cin cout File.in
File.out
Stream Diagram 2.0

13. Stream Diagram 2.0 Program.exe Keyboard Monitor cin cout File.in
File.out
Stream Diagram 2.0

14. File Streams Include the header file for file streams
#include <fstream>
Declaration of a input file stream
ifstream fin; // you can use any variable name
Declaration of a output file stream
ofstream fout; // you can use any variable name
Is that it? Can we use these file streams now?

15. File Streams Is that it? Can we use these file streams now?
No! We need to establish a connection between the file and the program.
By using the open function we associate a file stream with a file.
fin.open ( “file.in” );
Remember to disassociate a stream with a file after you are done with it.
fin.close ( );

16. Stream Diagram 2.0 Program.exe Keyboard Monitor cin cout File.in
File.out
fout
fin
Stream Diagram 2.0

17. File Streams
Questions

18. File Streams
Questions
How do we use these streams now?