1. The program starts by printing your initial with an end sign ">". For example, "cjx >";
2. Then, you can type in the following "vi filename". For example, "vi myp.c". You program will then open "myp.c" for reading. If the file does not exist, then there is nothing to read.
3. Read the file into a fixed array of "mytext[ 80]". Presumably, the "myp.c" text file is not too large with each line 80 characters or fewer. If there are more in the file, just ignore.
4. Close your file if it is open.
5. Change all your texts to upper case, and display the first 80 lines on your screen.
6. Then, your program will wait for a command from the keyboard.
7. If you type ":w", your program will open the same file for writing, and write your array of text into that file.
8. If you type ":q", your program will quite.
9. Replace "5. Change all your texts to upper case, and display the first 80 lines on your screen" with "Display the first 20 lines on the screen";
10. Display one special character using ascii code "176" or "178" at the position of mytext. You are not supposed to change the array though;
11. You can use "j" to move the special character down one line, "k" up one line, "h" left one character, "l" right one character. Of course, if there is no place to move left, right, up, or down, the special character just stays. In order to display the moved character, you may redisplay the first 20 lines again.
12. If you move beyond the first 20 lines, you should display the lines that are available with the special character at the top or bottom of the displayed 20 lines if you are moving out of the current 20 lines.