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Chapter 12: Problem 51

True or False ofstream objects, by default, delete the contents of a file if it already exists when opened.

Short Answer

Expert verified
Answer: True

Step by step solution

01

Understanding ofstream objects

`ofstream` stands for output file stream. It is a part of the C++ standard library and is used to perform writing operations to files. By default, `ofstream` opens a file in write mode (and binary mode or truncated mode, if specified). If a file with the given name already exists, its content is overwritten. So, by default, the statement in the question is true.
02

Explaining the default behavior of ofstream

When an `ofstream` object is created and used to open a file, the file is opened in write mode (unless specified otherwise). This means that any previous content in the file will be deleted and replaced with the new content written using the `ofstream` object. For example: ```cpp #include #include int main() { std::ofstream outfile("example.txt"); outfile << "This is new content."; outfile.close(); return 0; } ``` In this code, if `example.txt` already exists, its previous contents will be deleted and replaced with the text "This is new content.".
03

How to preserve the contents of a file

In case you want to preserve the contents of a file and append new content to it, you can open the file using the `std::ios::app` mode. For example: ```cpp #include #include int main() { std::ofstream outfile("example.txt", std::ios::app); outfile << "This is appended content."; outfile.close(); return 0; } ``` In this code, if `example.txt` already exists, its previous contents will be preserved and the new content "This is appended content." will be added to the end of the file. This method does not delete the original contents of the file.
04

Conclusion

The statement "ofstream objects, by default, delete the contents of a file if it already exists when opened" is True. By default, when an `ofstream` object is created and used to open a file, it opens the file in write mode, overwriting any previous content. If you wish to preserve the original content of a file, you need to open it using the `std::ios::app` mode.

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Most popular questions from this chapter

The inforile file stream object is used to sequentially access data. The program has already read to the end of the file. Write code that rewinds the file.

True or False The same output formatting techniques used with cout may also be used with file stream objects.

Assume that the file data. \(t x t\) already exists, and the following statement executes. What happens to the file? fstream file("data.txt", ios: : out) ;

The ___ member function reads "raw" binary data from a file.

Under what circumstances is a file stream object's ios : : badbit bit set? What member function reports the state of this bit?
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