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Engineering LibreTexts

20.5: Practice 19 File I/O and Array Functions

  • Page ID
    10371
  • Learning Objectives

    With 100% accuracy during a: memory building activity, exercises, lab assignment, problems, or timed quiz/exam; the student is expected to:

    Define the terms on the definitions as listed in the modules associated with this chapter.

    Within C++ source code be able to understand basic file input and file output.

    Understand why we test to see if a file was opened properly.

    Understand why we close a file when we are done with it.

    Within C++ source code be able to understand functions for arrays, specifically counting the number of elements in a file so you can define an array, load that array with those elements, display the array and sum the array.

    Within C++ source code be able to create functions for arrays, specifically a function for averaging.

    Memory Building Activities

    Link to: MBA 19

    Exercises

    Questions
        1. Text files are hard to create.
        2. A filespec refers to a very small (like a spec dust) file.
        3. A device token is a special non zero value the operating system gives your program and
        is associated with the file that you requested to be opened.
        4. Programmers should not worry about closing a file.
        5. Where you define an item, that is a global or local scope, is rarely important.
    Answers
        1. False
        2. False
        3. True
        4. False
        5. False
    

    Lab Assignment

    Creating a Folder or Sub-Folder for Chapter 19 Files

    Depending on your compiler/IDE, you should decide where to download and store source code files for processing. Prudence dictates that you create these folders as needed prior to downloading source code files. A suggested sub-folder for the Bloodshed Dev-C++ 5 compiler/IDE might be named:

    • Chapter_19 within the folder named: Cpp_Source_Code_Files

    If you have not done so, please create the folder(s) and/or sub-folder(s) as appropriate.

    Download the Lab File(s)

    Download and store the following file(s) to your storage device in the appropriate folder(s). You may need to right click on the link and select "Save Target As" in order to download the file.

    Download from Connexions: Lab_19_Narrative_Description.txt

    Detailed Lab Instructions

    Read and follow the directions below carefully, and perform the steps in the order listed.

    • Create a source code file following the directions in the Lab_19_Narrative_Description.txt file. Name it: Lab_19.cpp
    • Build (compile and run) your program.
    • After you have successfully written this program, if you are taking this course for college credit, follow the instructions from your professor/instructor for submitting it for grading.

    Problems

    Problem 19a - Instructions

    For what purpose do we use the sizeof operator with an array.

    Problem 19b - Instructions

    Why would we open a file and count its elements and then close the file.