Small Steps IV — Saving and Loading

Keeping values after a program ends

Keep values after a program ends.

What you will learn

A file holds data that can remain on a storage device after the program ends. A text file records characters you can read in a text editor.

Try it

void small_main()
{
    File file;

    file.open("score.txt", FileMode::Write);
    file.print("Alex");
    file.print(1200);
    file.close();

    print("Saved score.txt");
}

Save the source before running. The program writes Alex and 1200 on separate lines in score.txt. FileMode::Write replaces existing contents. Use a practice file you created yourself.

Follow open → write → close. A relative-path file usually appears in the saved source's folder. Open it in a text editor and check the two lines.

Exercise

Save a name on one line and an age on another in profile.txt, then close the file.

void small_main()
{
    File file;

    // Save a name and age to profile.txt.
}

Hint

Open in Write mode and use file.print twice.

void small_main()
{
    File file;

    file.open("profile.txt", FileMode::Write);
    file.print("Alex");
    file.print(12);
    file.close();

    print("Saved");
}