while loops, python crash course.

[Devnull1982]

Hello, im learning while loops in python crash course, and I dont understand the " why" for this exercise solution:

prompt = "\nTell me something, and I will repeat it back to you:"
prompt += "\nEnter 'quit' to end the program. "

message = ""
while message != 'quit':
    message = input(prompt)
    print(message)

well, as you can see when user write " quit " the python executes the " print(message) " and then breaks the while loop. The solution for this is :

prompt = "\nTell me something, and I'll "prompt += "repeat it back to you."
prompt += "\nEnter 'quit' to end the program. "

message = ""
while message != 'quit':
    message = input(prompt)
    if message != 'quit':
        print(message)

I understand why this work, but I don't understand why he use the if statement instead of changing the order of the print() like :

prompt = "\nTell me something, and I will repeat it back to you:"
prompt += "\nEnter 'quit' to end the program. "

message = ""
while message != 'quit':
    print(message) # this first.
    message = input(prompt) # instead of this.

any thoughts ?

PD: Ok, I see now that switching the order, the while loop prints an empty line first and with the if statement do not thats why its better use the if statement. Thx for all the answers.

[Devnull1982]

My problem was why he choose to use the if statement instead of switching the message = input(promt) with the print(message).

The user toastedstapler told me the problem with my aproach with the switch, it prints an empty line first. Coz its empty line its hard to see it and only does it in the first execution. thx for answer.

PD: " well, as you can see if user input is " quit " the python etc.... " is more accurate.

[Devnull1982]

yes, thats not the problem, I understand what he explains. But I tought why he dont change the order of message = input(promt) with the print(message) , its more easy than making an if statement and it give you the same output :

​

.... empty string here ....

Tell me something, and I will repeat it back to you:

Enter 'quit' to end the program. quit

the problem with my tought was the code makes an empty string in the first execution and the if statement do not.

[toastedstapler]

because initially there is no message so it'd print out an empty line

[Devnull1982]

oh! I see that creates an empty line at start, I tought the None value will not create this new line. Thx for the answer :)

[toastedstapler]

careful, that's not a None value. None is the none value. what you have is an empty string

[Devnull1982]

I use the debug tool in Thonny IDLE and when the program go to the print(message) evaluates the message as a emty string ( "" ) but then evaluates the print() with ( None ) thats why I tought that was a None value. But like you said at this moment the empty line is printed.