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Welcome back. I'm here with some way of the program or

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tips on how to make it so that you can understand what's going on in your programs.

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Here, I've got some code for doing

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an accumulator pattern to add up all the numbers from one to 10.

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But suppose you didn't recognize it as that.

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You could use CodeLens if you have a small enough program like,

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this one, but it's good to start learning how

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to add some print statements that will print out intermediate results.

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So, suppose I run this in Enterprise that I got 45 rather than 55. What should I do?

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The answer is, I should start adding some print statements.

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So, here I've added inside the for loop something that prints the number,

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the current value of the iterator variable.

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So, what's the value of num on this iteration.

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So, now I find out that at zero,

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then one, then two, then three, then four,

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if I was thinking that range of 10 was going to give me the numbers from one to 10,

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adding this print statement on line five will give me

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a clue that actually it's giving me the numbers from zero to nine.

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Now, suppose I'm still a little puzzled.

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Maybe I don't really understand what lines six is doing with this tot plus equals num.

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Here, I've added an extra print statement on line eight to print tot,

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the value of the accumulator variable at the end of each iteration.

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So, now we find that we get zero and zero.

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So, this is num is zero and tot is zero,

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and num and tot are both one,

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and num is two and tot is three,

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because we've added the previous total one

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plus the new number two and we get three and so on.

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So, now I can start to understand that line seven is taking the old value of total,

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adding in the current value of num and writing that back into tot.

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So, we get the old value of total was one,

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the new value of num is two and we write it back into tot,

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so that it's three, and on the next iteration will have three in tot.

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Now, I had to do a lot of writing stuff

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here to remind us of which variables were getting printed out.

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So, when you're printing intermediate results,

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sometimes it's helpful to print out a little text saying what it is that you're printing,

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and that's what I've done in the next window.

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So, I've got a print statement on line four saying,

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"Hey, we are before the for loop."

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Then, on line six,

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you say we're doing a new iteration and the value of num is something.

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You can see that with all of this diagnostics,

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it's much easier to read the output.

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So, instead of me having to write in num and tot,

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we've got it all getting printed out already.

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The value of num was zero and the value of tote was zero,

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and they were both one,

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then num was two and tot was three because we added the two and the one.

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We have a value of tot is three and the value of num is three,

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so we add those two together to get six,

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six and four makes 10 and so on.

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So, it's helpful to add print statements.

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If you just add one,

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you don't need to have all this diagnostic stuff

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like saying what it is you're printing out?

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But once you start to have a several print statements,

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it's helpful if you include things like,

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now you have done this,

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so that when you go to look at it over here,

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you know what you're seeing in the printout.

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So, that's a little tip on printing intermediate results. I'll see you next time.