C++ All-in-One For Dummies, 3rd Edition

Chapter 3

Reading with Input Streams

In This Chapter

Reading with the extraction operators

Dealing with the end of the file

Reading various data types

Reading data that is formatted with text

Well, isn’t this nice. You have a file that you wrote to, but you need to read from it! After all, what good is a file if it’s just sitting on your hard drive collecting dust?

In this chapter, we show you how you can read from a file. Reading a file is tricky because you can run into some formatting issues. For example, you may have a line of text in a file with a sequence of 50 digits. Do those 50 digits correspond to 50 one-digit numbers, or maybe 25 two-digit numbers, or some other combination? If you created the file, you probably know; but the fun part is getting your C++ application to properly read from them. The file might contain 25 two-digit numbers, in which case you make sure that the C++ code doesn’t just try to read one enormous 50-digit number. In this chapter, we give you all the dirt on getting the dust off your hard drive and the file into memory. Have at it!

Extracting with ...