This is Python Program 5: Improve the file copy program from Lab 9 so that it will make sure the user enters a file that exists. If a file doesn’t exist, the open function will raise the FileNotFoundError. You do not need to check if the destination exists since a file doesn’t need to exist to write it. Instead of copying the content of the source as exact, it only copies non-empty lines and it also prepend each line with a line number. A line is empty if the length of the line stripped of white space from both end is 0. The code segment below shows how to strip white space and getting the length of the string. If the length of the line is zero, the line is a blank line. line1 = " " line2 = " aa " print(len(line1.strip())) # 0 print(len(line2.strip())) # 2 In the sample run, “add.py” is the source file and “add-copy.py” is the destination file. Note that “add-copy.py” contains only non-blank lines from “add.py” and each line in “add-copy.py” is labelled with a line number. Sample run: Enter file to copy from: add.txt File doesn't exist. Try again. Enter file to copy from: add.java File doesn't exist. Try again. Enter file to copy from: add.py Enter file to copy to : add-copy.py Copy is successful. Source file: add.py print("This program adds two numbers") a = int(input("Enter first number: ")) b = int(input("Enter second number: ")) print(f"{a} + {b} = {a+b}") Destination file: add-copy.py 1: print("This program adds two numbers") 2: a = int(input("Enter first number: ")) 3: b = int(input("Enter second number: ")) 4: print(f"{a} + {b} = {a+b}")
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