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Hey guys, welcome to Day 8 of a 100 Days of Code.

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And today we're going to be looking at functions that allow you to give them

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inputs. And once we've learned all of that and we've grasped it,

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then we're going to be building a cipher program.

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And the cipher program is called Caesar cipher.

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So Caesar cipher is a really quite ancient type of encryption.

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So the story goes that, um,

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when Caesar wanted to send highly sensitive military messages,

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he would encode his message so that each letter would be shifted by a

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predetermined amount.

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So let's say that we wanted to encode the letter "A" and we shift it by three,

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well

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then A becomes D, B becomes E and so on and so forth.

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And this is what the final version will look like.

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Let's go ahead and encode something.

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So I'm going to type encode to start encrypting a message.

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And then I'm going to type my message with no spaces in between.

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And then I'm going to give it a shift number.

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So this is going to be a number that

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the recipient and I are going to agree on so that we know how to decode the

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message. Let's put that at nine.

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And then it's going to give us the encoded results

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which is something like this.

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And this will be the message that I'm going to transmit to my friend,

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either through a letter or through an email

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and it means that whenever somebody comes across this message

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they won't really know what's going on unless they knew the shift number.

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So let's say that I am my friend. I've just received this message.

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And I'm going to go ahead and type yes to go again

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and in this case, I'm going to decode instead of encoding.

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And then I'm going to paste the message and hit enter.

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And of course, the shift number is nine and now I have the decoded results

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which I can read and understand. By the end of today,

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you would have learned about functions with input,

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you'll know what the difference is between arguments and parameters.

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Once you're ready, once you're loaded up on coffee,

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then head over to the next lesson and let's get started.