string characterName = "Sephiroth";
int level = 24;

int score = 0;
Console.WriteLine(score);

score = 3;
Console.WriteLine(score);

0
3

score = score + 2;

int score = 3;
score = score + 2;

Console.WriteLine(score);

5

score + 2;

1-6-arithmetic.cs(2,1): error CS0201: Only assignment, call, increment, decrement, await, and new object expressions can be used as a statement
The build failed. Fix the build errors and run again.

Console.WriteLine(8 + 3);
Console.WriteLine(8 - 3);
Console.WriteLine(8 * 3);
Console.WriteLine(8 / 3);

11
5
24
2

11
5
24
2

11
5
24
2

double average = 47 / 6;
Console.WriteLine(average);

7

Console.WriteLine(47.0 / 6);

7.833333333333333

Console.WriteLine(17 / 5);
Console.WriteLine(17 % 5);

3
2

Console.WriteLine(9 % 2);
Console.WriteLine(12 % 2);
Console.WriteLine(14 % 12);

1
0
2

Console.WriteLine(2 + 3 * 4);
Console.WriteLine((2 + 3) * 4);

14
20

Console.WriteLine(20 % 7 * 2);
Console.WriteLine(20 % (7 * 2));

12
6

Console.Write("Score: ");
Console.WriteLine(score);

Score: 7

Console.WriteLine($"Score is {score}.");

Score is 7.

Console.WriteLine($"Two more would put the total at {score + 2}.");
Console.WriteLine($"score is still {score}.");

Two more would put the total at 9.
score is still 7.

'F' → Fullscreen

Build

Create a new C# program named 1-6-arithmetic, starting empty.

Use the same subject you chose for Activity 1.5 — the athlete, character, or officer whose card you built. Today they get a score that moves.

The examples below continue with the RPG character from Activity 1.5. If you built a different kind of card, swap in your own subject and events — the arithmetic works the same either way.

This activity runs over two sessions. Tasks 1 to 4 are the first; Tasks 5 and 6 are the second.

Task 1: A Value That Changes

• Declare a string for the name and an int score starting at 0.
• Print the name, then the score.
• On a new line, put 3 into the score. Do not write int again.
• Print the score a second time.

Two lines of output, two different numbers, one variable. That is the whole idea.

1
string characterName = "Sephiroth";
2
int score = 0;
3

4
Console.Write(characterName);
5
Console.WriteLine(" enters the dungeon.");
6
Console.Write("Score: ");
7
Console.WriteLine(score);
8

9
score = 3;
10
Console.Write("Score: ");
11
Console.WriteLine(score);

Task 2: Update It From Itself

• Add two more kills, each worth 2, and print the score after each.
• Do not type 5 or 7 anywhere. The program works them out.

1
string characterName = "Sephiroth";
2
int score = 0;
3

4
Console.Write(characterName);
5
Console.WriteLine(" enters the dungeon.");
6
Console.Write("Score: ");
7
Console.WriteLine(score);
8

9
score = 3;
10
Console.Write("Score: ");
11
Console.WriteLine(score);
12

13
score = score + 2;
14
Console.Write("Score: ");
15
Console.WriteLine(score);
16

17
score = score + 2;
18
Console.Write("Score: ");
19
Console.WriteLine(score);

Task 3: Splitting the Raid

• Forty-seven adventurers sign up. Parties hold six.
• Work out the number of full parties and the number of adventurers left over.
• Both values must be calculated, not typed in.
• Check it by hand first: 6 × 7 = 42, and 47 − 42 = 5.
• This goes below what you already have, after a blank Console.WriteLine() to separate the two halves of the output.

1
string characterName = "Sephiroth";
2
int score = 0;
3

4
Console.Write(characterName);
5
Console.WriteLine(" enters the dungeon.");
6
Console.Write("Score: ");
7
Console.WriteLine(score);
8

9
score = 3;
10
Console.Write("Score: ");
11
Console.WriteLine(score);
12

13
score = score + 2;
14
Console.Write("Score: ");
15
Console.WriteLine(score);
16

17
score = score + 2;
18
Console.Write("Score: ");
19
Console.WriteLine(score);
20

21
Console.WriteLine();
22

23
int adventurers = 47;
24
int perParty = 6;
25
int fullParties = adventurers / perParty;
26
int leftOver = adventurers % perParty;
27

28
Console.Write("Adventurers:");
29
Console.WriteLine(adventurers);
30
Console.Write("Parties:    ");
31
Console.WriteLine(fullParties);
32
Console.Write("Left over:  ");
33
Console.WriteLine(leftOver);

Whole-number division did the hard part for you. 47 / 6 is 7 on its own — there is nothing to round down, because the fraction was never kept.

Task 4: Break It on Purpose

Five experiments. Write down exactly what appears each time, copied from the screen rather than from memory. Undo each one before the next.

1. Print 8 / 3.
2. Add double average = 47 / 6; and print average.
3. Print 47.0 / 6.
4. Print 10 % 3 * 2, then print 10 % (3 * 2).
5. Put score + 2; on a line by itself, with nothing to the left of it.

One of these refuses to run. The other four produce a number, and at least two of them will not be the number you expected. Which is which is what the sheet asks for.

There is no code block for this task. Each experiment is temporary and gets undone before the next one, so when Task 4 is over your program is exactly what it was at the end of Task 3.

Task 5: Say It in One Line

• Replace every Console.Write and Console.WriteLine pair with a single interpolated line.
• Make each line read like a sentence rather than a label and a number.
• Count your program's lines before and after. Write both numbers down — it should go from 33 lines to 24.
• This task replaces lines rather than adding them, so your program gets shorter. Each + line below stands in for a Console.Write and Console.WriteLine pair you already had.

1
string characterName = "Sephiroth";
2
int score = 0;
3

4
Console.WriteLine($"{characterName} enters the dungeon at {score}.");
5

6
score = 3;
7
Console.WriteLine($"First kill. Score is {score}.");
8

9
score = score + 2;
10
Console.WriteLine($"Side quest. Score is {score}.");
11

12
score = score + 2;
13
Console.WriteLine($"Another kill. Score is {score}.");
14

15
Console.WriteLine();
16

17
int adventurers = 47;
18
int perParty = 6;
19
int fullParties = adventurers / perParty;
20
int leftOver = adventurers % perParty;
21

22
Console.WriteLine($"{adventurers} adventurers, {perParty} to a party.");
23
Console.WriteLine($"Parties:    {fullParties}");
24
Console.WriteLine($"Left over:  {leftOver}");

Task 6: The Entry Bill

• A full party pays 25 to enter. A leftover adventurer pays 7 to join a mixed party.
• Print the party total, the solo total, and the sum of both.
• Do the arithmetic inside the holes. No new variables for the three totals.
• This goes below Task 5's program, separated by another blank Console.WriteLine().
• Now change adventurers to 100 and run it again. Every number should move. Set it back to 47.

1
string characterName = "Sephiroth";
2
int score = 0;
3

4
Console.WriteLine($"{characterName} enters the dungeon at {score}.");
5

6
score = 3;
7
Console.WriteLine($"First kill. Score is {score}.");
8

9
score = score + 2;
10
Console.WriteLine($"Side quest. Score is {score}.");
11

12
score = score + 2;
13
Console.WriteLine($"Another kill. Score is {score}.");
14

15
Console.WriteLine();
16

17
int adventurers = 47;
18
int perParty = 6;
19
int fullParties = adventurers / perParty;
20
int leftOver = adventurers % perParty;
21

22
Console.WriteLine($"{adventurers} adventurers, {perParty} to a party.");
23
Console.WriteLine($"Parties:    {fullParties}");
24
Console.WriteLine($"Left over:  {leftOver}");
25

26
Console.WriteLine();
27

28
int partyFee = 25;
29
int soloFee = 7;
30

31
Console.WriteLine($"Party entries: {fullParties * partyFee}");
32
Console.WriteLine($"Solo entries:  {leftOver * soloFee}");
33
Console.WriteLine($"Total:         {fullParties * partyFee + leftOver * soloFee}");

Challenge (Optional): Predict Before You Run

• Write these four as comments, and next to each write what you think it will print:
• 10 - 2 * 3   (10 - 2) * 3   7 / 2   7 % 2
• Now print them and compare. The ones you got wrong are the ones worth remembering.

Same Idea, Exam Notation

int total = 17 + 5;
int extra = 17 % 5;
score = score + 2;

total ← 17 + 5
extra ← 17 MOD 5
score ← score + 2

• +, -, *, and / are written the same way in both.
• Remainder is spelled MOD instead of %. Same operation, same priority.
• Assignment is an arrow. score ← score + 2 is the same instruction as score = score + 2;, read the same way: right side first.

The sheet also lists one thing you have no C# match for yet:

roll ← RANDOM(1, 6)

RANDOM(a, b) gives a whole number from a to b, and both ends are included — so RANDOM(1, 6) can give a 1 or a 6. Getting randomness in C# takes a little more, and Activity 1.16 does it.

Checkpoint

Your finished program should produce this.

Sephiroth enters the dungeon at 0.
First kill. Score is 3.
Side quest. Score is 5.
Another kill. Score is 7.

47 adventurers, 6 to a party.
Parties:    7
Left over:  5

Party entries: 175
Solo entries:  35
Total:         210

• The score reaches 7 without 7 appearing anywhere in your program.
• No Console.Write and Console.WriteLine pair is left.
• Changing adventurers to 100 moves every number below it.
• All five Task 4 results are written down, copied from the screen.

Reflection

Answer the following questions before submitting your work.

1. score = score + 2; would be false as a math equation. Describe, in order, what C# actually does with that line.
2. 47 / 6 gave 7 and 47.0 / 6 gave 7.833333333333333. Only one character changed. Explain why that changed the answer.
3. The exam reference sheet says 17 / 5 is 3.4. C# says it is 3. Both are correct. How would you explain that to someone who thinks one of them must be wrong?
4. Your Task 5 rewrite is shorter than the version it replaced. Name one thing that got easier to read, not just shorter.

Submit

Submit four things to the dropbox:

1. Your 1-6-arithmetic program file.
2. A copy of its output.
3. Your five Task 4 results and your two line counts from Task 5.
4. Your four reflection answers.

Activity Complete