Book Image

Modern C++ Programming Cookbook

By : Marius Bancila
Book Image

Modern C++ Programming Cookbook

By: Marius Bancila

Overview of this book

C++ is one of the most widely used programming languages. Fast, efficient, and flexible, it is used to solve many problems. The latest versions of C++ have seen programmers change the way they code, giving up on the old-fashioned C-style programming and adopting modern C++ instead. Beginning with the modern language features, each recipe addresses a specific problem, with a discussion that explains the solution and offers insight into how it works. You will learn major concepts about the core programming language as well as common tasks faced while building a wide variety of software. You will learn about concepts such as concurrency, performance, meta-programming, lambda expressions, regular expressions, testing, and many more in the form of recipes. These recipes will ensure you can make your applications robust and fast. By the end of the book, you will understand the newer aspects of C++11/14/17 and will be able to overcome tasks that are time-consuming or would break your stride while developing.
Table of Contents (19 chapters)
Title Page
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface

Removing content from a file


Operations such as copying, renaming, moving, or deleting files are directly provided by the filesystem library. However, when it comes to removing content from a file, you must perform explicit actions. Regardless of whether you need to do this for a text or binary files, you must implement the following pattern:

  1. Create a temporary file.
  2. Copy only the content that you want from the original file to the temporary file.
  3. Delete the original file.
  4. Rename/move the temporary file to the name/location of the original file.

Getting ready

In this recipe, we will see how to implement the pattern mentioned earlier for a text file. To do this, we will consider removing empty lines or lines that start with a semicolon (;). For this example, we will have an initial file called sample.dat that contains the names of Shakespeare's plays, but also empty lines and lines that start with a semicolon. The following is a partial listing of this file (from the beginning):

;Shakespeare's plays...