changing a local variable inside a while loop



So after I wrote out the first part of lesson 8,  I got curious.  Why didn't changing the variable s, inside the while loop, end the loop?  
if the loop requires s to equal Y or y,   and the new s in the loop is not Y or y,  why didn't it shut the loop down?  

I found very little to explain,  but it seems what the great mighty google says is that a local variable changed inside the loop will not be saved... But the program will not loop again unless I add that last bit of code highlighted,  code in which I can have the user answer yes again and have it restart.  

Eclipse would not allow me to create a new String s = input(); into the loop, because it would change the local variable.  But changing s to a new input ("yes") allows the program to run again. So clearly I changed the variable for the math, then changed it back again to yes....

shouldn't the loop stop the first time s is changed to not fit the statement?
Going to surf some more and see if anything pops up.

Solution: http://math.hws.edu/javanotes/c3/s3.html

The while loop doesn't evaluate if the statement is True/False until it has run to the end of the loop.
So you can change the variable as much as you want, but it won't stop the loop unless it evaluates to false at the end.  

Comments

Post a Comment

Popular posts from this blog

playing with color in powershell python

Here's a bit I'm working on.  I've discovered I love doing Ascii.  Examples of how to use the color changing escape.  I got a table from StackOverflow: https://stackoverflow.com/questions/287871/print-in-terminal-with-colors-using-python the charts are way at the bottom. So far accurate for me.  def prettyjunk ( self ): # 1 is bold, 0 is plain, 2 is dull text_red = ' \x1b [1;31;40m' stop_color = ' \x1b [0m' text_blue = ' \x1b [1;34;40m' text_green = ' \x1b [1;32;40m' text_purple = ' \x1b [1;35;40m' text_lightblue = ' \x1b [1;36;40m' text_white = ' \x1b [1;37;40m' a_green_at = ( f " { text_green } @ { stop_color } " ) a_red_at = ( f " { text_red } @ { stop_color } " ) print ( f " { text_red } This should be Red. { stop_color } " ) print ( f "
Read more

JavaScript Ascii animation with while loops and console.log

I was working on figuring out while loops for an exercise in LearnJavaScriptTheHardWay  by Zed Shaw,  and I decided to do this: The red text console.logs were for debugging, and will take over the animation if the comments are removed. The bold red number is the point at which the loop stops.  My CPU didn't have too much trouble with that large number, but I'd recommend dialing it down if your CPU is slow. Also if your CPU is really fast, you'll have to change the pause to something much lower to see the animation better.  That too is in a loop, so the more that pause happens, the more loops your CPU is running.   Link: https://stackoverflow.com/questions/9006988/node-js-on-windows-how-to-clear-console To clear screen as described in link above, uncomment the bold purple comment I tried to comment the code to help learners see what I did,  any comments or suggestions, feel free to drop em in!                      ex16_ASCII.js //Trying to make a comma
Read more

playing with trigonometry sin in pygame

Image
Ok I am so far from understanding, so don't take this as any kind of math lesson. Also, every time I thought I knew what I was doing.... pygame would show me differently. Still a work in progress, but for now, something to play with. Update: SinWaveTime class added to produce that particular weaving effect Tinkering with the different sin wave variables: I wrote this piece separate from my 3D experiment to see how to manipulate the sin wave. While trying to use time as the factor to move my pygame draw circle on the x-axis, i got this crazy little doo-dad : I don't think it's drawing two circles at once, but if I figure out what the heck it's doing I'll let you know.  Or hey if you know, drop a comment.  I don't know if my comments are just not working, or no one wants to. So, here's some pygame code to play with the sin wave.  Alter the different variables to see it in action. picture of SinWave.move_with_time() see changes, SinWaveTime c
Read more