Chapter 12: Problem 41

Write a statement that defines a file stream object named places. The object will be used for both output and input.

Short Answer

Expert verified

Answer: To define a file stream object named places and use it for both input and output, follow these steps: 1. Include the library `fstream` using `#include `. 2. Define the `fstream` object by writing `std::fstream places;`. 3. Open the file for input and output with `places.open("places.txt", std::ios::in | std::ios::out);`. 4. Work with the file using the object, for example, output with `places << "Paris\n";` and input with `getline(places, line);`. 5. Close the file using `places.close();`.

Step by step solution

Including the Library

The first step is to include the library which contains the classes and functions needed for file input and output. You'll need to include the library `fstream` at the top of your code. The line of code should be: `#include `

Defining the Object

Next, you'll write a statement that defines a `fstream` object called places. To define an object of the class fstream we must use the following syntax: `std::fstream places;` This statement is creating an object of the `fstream` class named "places". The `std::` is called a namespace and fstream is the class name.

Opening the File for Input and Output

To use the object for input and output, you'll need to open a file. This will be done using the `open` function. Objects of class `fstream` allow both input and output operations (formatting and extraction) directly on these objects. You must specify the mode to both read and write, and "places.txt" is the file to be opened: `places.open("places.txt", std::ios::in | std::ios::out);` The `std::ios::in` flag opens the file for reading and the `std::ios::out` flag opens the file for writing.

Working with the File

From this point, you can begin inputting and outputting data to and from the file using the object. For example for output, you can use: `places << "Paris\n";` which will write the string "Paris" to the file followed by a newline character. For input, you can use: `std::string line;` `getline(places, line);` which will read a line from the file and store it in the string "line".

Closing the File

After you're done with the file, don't forget to close it using the `close` function. Your statement should look like this: `places.close();`. This ensures all changes have been completed and resources have been freed.

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Write a statement that defines a file stream object named places. The object will be used for both output and input.

Short Answer

Step by step solution

Including the Library

Defining the Object

Opening the File for Input and Output

Working with the File

Closing the File

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