Chapter 23 – Using File Input and File Output

1. Because of the variety of input and output, we needed to verify each possible execution path within our program.
2. If a specified input file does not exist, it makes no sense to continue processing. The program must exit.
3. When an output file is opened for writing, its current contents are cleared and a file is created with new data. When an output file is opened for appending, any new data is added to the end of the file; the pre-existing file data is preserved.
4. Handling the final <newline> character when using fgets() depends upon the context in which fgets() is used. In the last chapter, we used a wrapper function around fgets(). In this chapter, we didn't need to do that, since the trimStr() function is always used after fgets(), which removes all leading and trailing whitespace.