This is a C file.
1. The program starts by printing your name with an end sign ">". For example, "NAME >";
2. Then, you can type in a string. If the string is not "vi xxx", you print "I don''t know this command." You keep getting a string until you get a string starting with "vi". 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[1000][ 81]". Presumably, the "myp.c" text file is not too large with each line 80 characters or fewer. If there are more characters than 80 in a line, you can just ignore the characters beyond 80.
4. Close your file.
5. Change all your texts to upper case, and display the first 20 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. If your type ":w myp1.c", your program will open "myp1.c" and write into that file. You should always close your file after finish. Remember to use function calls instead of a program of one function.
Each function should be shorter than two pages.