Stupid way to learn Python (20)

Exercise 20: Functions and files

Recall the main points of the function, and then do this exercise while noticing how the functions and files work together.

1  fromSysImportargv2 3Script, Input_file =argv4 5 defPrint_all (f):6     PrintF.read ()7 8 defRewind (f):9 f.seek (0)Ten  One defPrint_a_line (Line_Count, f): A     PrintLine_Count, F.readline () -  -Current_file =Open (input_file) the  - Print "First let ' s print the whole file:\n" -  - Print_all (current_file) +  - Print "Now let's rewind, kind of like a tape." +  A Rewind (Current_file) at  - Print "Let ' s print three lines:" -  -Current_line = 1 - print_a_line (Current_line, Current_file) -  inCurrent_line = current_line + 1 - print_a_line (Current_line, Current_file) to  +Current_line = current_line + 1 -Print_a_line (Current_line, Current_file)

View Code

Pay special attention to how we pass the current line number information each time we run print_a_line .

The results you should see

Bonus points Exercise

2. Read through the script and add annotations before each line to understand what's going on in the script.
4. Each time Print_a_line runs, you pass a variable called current_line . Each time the function is called, the current_line is printed out to track how it becomes line_count in the print_a_line .
6. Find out where each function is used in the script. Check the def line to verify that the parameter is not used correctly.
8. Go online and study what the seek function in file does. Try running pydoc file to see if you can learn more.
10. Consider the function of the shorthand operator of + = , write a script, and use this operator to try it out.

Exercise Exercises

1.

Stupid way to learn Python (20)