Chapter 12: Problem 21

What classes do you use to write output to a binary file? What classes do you use to read from a binary file?

Short Answer

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Answer: In C++, the main classes used for writing to and reading from binary files are `std::ofstream` and `std::ifstream`, respectively. Remember to use the `std::ios::binary` flag when opening the file. In Java, the main classes used for this purpose are `java.io.FileOutputStream` and `java.io.ObjectOutputStream` for writing, and `java.io.FileInputStream` and `java.io.ObjectInputStream` for reading.

Step by step solution

Understand Binary Files

Binary files store data in binary format, which is in zeros (0) and ones (1). They are useful for storing large amounts of data efficiently without the need to convert them to human-readable formats.

Writing to a Binary File

To write to a binary file, one generally uses output stream classes that have methods to handle binary data. In many programming languages, such as C++ and Java, there are specific classes for this purpose: - In C++: - `std::ofstream`: This is an output file stream class used to create and write to binary files. - To write in binary mode, use the `std::ios::binary` flag when opening the file. Sample code for writing to a binary file in C++: ``` #include #include int main() { std::ofstream outFile("example.bin", std::ios::binary | std::ios::out); int dataToWrite = 42; outFile.write(reinterpret_cast(&dataToWrite), sizeof(dataToWrite)); outFile.close(); } ``` - In Java: - `java.io.FileOutputStream`: This class is used to create and write to binary files. - `java.io.ObjectOutputStream`: It wraps the FileOutputStream class to provide additional data handling methods. Sample code for writing to a binary file in Java: ``` import java.io.FileOutputStream; import java.io.ObjectOutputStream; public class Main { public static void main(String[] args) { try { FileOutputStream fos = new FileOutputStream("example.bin"); ObjectOutputStream oos = new ObjectOutputStream(fos); int dataToWrite = 42; oos.writeInt(dataToWrite); oos.close(); fos.close(); } catch (Exception e) { e.printStackTrace(); } } } ```

Reading from a Binary File

To read from a binary file, one generally uses input stream classes that have methods to handle binary data: - In C++: - `std::ifstream`: This is the input file stream class used to read binary files. - Remember to use the `std::ios::binary` flag when opening the file. Sample code for reading from a binary file in C++: ``` #include #include int main() { std::ifstream inFile("example.bin", std::ios::binary | std::ios::in); int dataRead = 0; inFile.read(reinterpret_cast(&dataRead), sizeof(dataRead)); inFile.close(); std::cout << "Data read from file: " << dataRead << std::endl; } ``` - In Java: - `java.io.FileInputStream`: This class is used to read binary files. - `java.io.ObjectInputStream`: It wraps the FileInputStream class to provide additional functionality. Sample code for reading from a binary file in Java: ``` import java.io.FileInputStream; import java.io.ObjectInputStream; public class Main { public static void main(String[] args) { try { FileInputStream fis = new FileInputStream("example.bin"); ObjectInputStream ois = new ObjectInputStream(fis); int dataRead = ois.readInt(); ois.close(); fis.close(); System.out.println("Data read from file: " + dataRead); } catch (Exception e) { e.printStackTrace(); } } } ``` Now you are familiar with the classes used to write output to a binary file and read from a binary file in different programming languages.

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What classes do you use to write output to a binary file? What classes do you use to read from a binary file?

Short Answer

Step by step solution

Understand Binary Files

Writing to a Binary File

Reading from a Binary File

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