int total = 0;

for (int i = 1; i <= 4; i++)
{
    total = total + i;
}

Console.WriteLine($"Total: {total}");

Total: 10

int hotDays = 0;

for (int i = 1; i <= 5; i++)
{
    Console.Write($"Reading {i}? ");
    int temp = int.Parse(Console.ReadLine());

    if (temp > 30)
    {
        hotDays = hotDays + 1;
    }
}

Console.WriteLine($"Readings above 30: {hotDays}");

Reading 1? 28 [Enter]
Reading 2? 34 [Enter]
Reading 3? 31 [Enter]
Reading 4? 22 [Enter]
Reading 5? 35 [Enter]
Readings above 30: 3

int highest = 0;

for (int i = 1; i <= 3; i++)
{
    Console.Write("Reading? ");
    int temp = int.Parse(Console.ReadLine());

    if (temp > highest)
    {
        highest = temp;
    }
}

Console.WriteLine($"Highest: {highest}");

Reading? -5 [Enter]
Reading? -12 [Enter]
Reading? -3 [Enter]
Highest: 0

int total = 12;
int count = 5;

double average = total / count;

Console.WriteLine($"Average: {average:F1}");

Average: 2.0

int total = 12;
double count = 5;

double average = total / count;

Console.WriteLine($"Average: {average:F1}");

Average: 2.4

'F' → Fullscreen

Build

Today you build a fishing game in a new program named 1-20-fishing-trip. Ten casts, and on each one you choose shallow water or deep. By the end it reports your trip using all four of today's patterns.

Task 1: Ten Casts

• Write the code below and play a trip. Each pass of the loop is one cast: you choose the water, and Random decides whether anything bites and how big it is.
• totalWeight is an accumulator. It adds the weight of every fish. Add your fish up by hand and check that the total matches.
• Notice where weight is declared. It is inside the loop, so it is brand new every cast — and that is fine, because totalWeight is the one that has to survive all ten. Be ready to say why totalWeight could not go inside.
• Play one trip all shallow and one all deep. Write down both totals. Which water would you rather fish?

1
int totalWeight = 0;
2

3
Console.WriteLine("Ten casts. Shallow water bites often. Deep water bites less, but bigger.");
4
Console.WriteLine();
5

6
for (int cast = 1; cast <= 10; cast++)
7
{
8
    Console.Write($"Cast {cast}: shallow (1) or deep (2)? ");
9
    int spot = int.Parse(Console.ReadLine());
10

11
    int weight = 0;
12
    int roll = Random.Shared.Next(1, 101);
13

14
    if (spot == 1 && roll <= 75)
15
    {
16
        weight = Random.Shared.Next(1, 7);
17
    }
18

19
    if (spot == 2 && roll <= 30)
20
    {
21
        weight = Random.Shared.Next(4, 16);
22
    }
23

24
    if (weight > 0)
25
    {
26
        Console.WriteLine($"  A {weight} lb fish!");
27

28
        totalWeight = totalWeight + weight;
29
    }
30
    else
31
    {
32
        Console.WriteLine("  Nothing bites.");
33
    }
34
}
35

36
Console.WriteLine();
37
Console.WriteLine($"Total weight: {totalWeight} lb");

Task 2: Count Them, and Keep the Biggest

• Two more patterns join the same loop. One pass of input, three questions answered — that is the normal shape of this.
• fishCaught adds one. totalWeight adds the weight. They look almost the same and they answer completely different questions.
• Both go inside if (weight > 0). A cast that catches nothing should not be counted, and it cannot be the biggest fish.
• biggest starts at 0, and here that is safe. The deck called starting a maximum at 0 the classic bug of this pattern. Work out why it cannot hurt this program — what is the lightest fish you can catch?

1
int totalWeight = 0;
2
int fishCaught = 0;
3
int biggest = 0;
4

5
Console.WriteLine("Ten casts. Shallow water bites often. Deep water bites less, but bigger.");
6
Console.WriteLine();
7

8
for (int cast = 1; cast <= 10; cast++)
9
{
10
    Console.Write($"Cast {cast}: shallow (1) or deep (2)? ");
11
    int spot = int.Parse(Console.ReadLine());
12

13
    int weight = 0;
14
    int roll = Random.Shared.Next(1, 101);
15

16
    if (spot == 1 && roll <= 75)
17
    {
18
        weight = Random.Shared.Next(1, 7);
19
    }
20

21
    if (spot == 2 && roll <= 30)
22
    {
23
        weight = Random.Shared.Next(4, 16);
24
    }
25

26
    if (weight > 0)
27
    {
28
        Console.WriteLine($"  A {weight} lb fish!");
29

30
        totalWeight = totalWeight + weight;
31
        fishCaught = fishCaught + 1;
32

33
        if (weight > biggest)
34
        {
35
            biggest = weight;
36
        }
37
    }
38
    else
39
    {
40
        Console.WriteLine("  Nothing bites.");
41
    }
42
}
43

44
Console.WriteLine();
45
Console.WriteLine($"Total weight: {totalWeight} lb");
46
Console.WriteLine($"Fish caught: {fishCaught} of 10");
47
Console.WriteLine($"Biggest: {biggest} lb");

Task 3: The Trip Report

• The minimum is the maximum pattern with two things flipped — < instead of >, and a starting value of 999 instead of 0. Be ready to say why it starts that high.
• The report is inside if (fishCaught > 0). No fish, no biggest, no smallest, and no average — there is nothing to report.
• Type everything except the change on line 2 first. Leave fishCaught as an int, play a trip, and work out total ÷ fish on a calculator. Compare it with the average your program printed.
• Then change int to double on line 2 and play again — the deck's one-word fix. Write down one wrong average and one right one. If your first trip happened to divide evenly, the bug hid; play until it does not.

1
int totalWeight = 0;
2
double fishCaught = 0;
3
int biggest = 0;
4
int smallest = 999;
5

6
Console.WriteLine("Ten casts. Shallow water bites often. Deep water bites less, but bigger.");
7
Console.WriteLine();
8

9
for (int cast = 1; cast <= 10; cast++)
10
{
11
    Console.Write($"Cast {cast}: shallow (1) or deep (2)? ");
12
    int spot = int.Parse(Console.ReadLine());
13

14
    int weight = 0;
15
    int roll = Random.Shared.Next(1, 101);
16

17
    if (spot == 1 && roll <= 75)
18
    {
19
        weight = Random.Shared.Next(1, 7);
20
    }
21

22
    if (spot == 2 && roll <= 30)
23
    {
24
        weight = Random.Shared.Next(4, 16);
25
    }
26

27
    if (weight > 0)
28
    {
29
        Console.WriteLine($"  A {weight} lb fish!");
30

31
        totalWeight = totalWeight + weight;
32
        fishCaught = fishCaught + 1;
33

34
        if (weight > biggest)
35
        {
36
            biggest = weight;
37
        }
38

39
        if (weight < smallest)
40
        {
41
            smallest = weight;
42
        }
43
    }
44
    else
45
    {
46
        Console.WriteLine("  Nothing bites.");
47
    }
48
}
49

50
Console.WriteLine();
51
Console.WriteLine($"Total weight: {totalWeight} lb");
52
Console.WriteLine($"Fish caught: {fishCaught} of 10");
53

54
if (fishCaught > 0)
55
{
56
    double average = totalWeight / fishCaught;
57

58
    Console.WriteLine($"Biggest: {biggest} lb");
59
    Console.WriteLine($"Smallest: {smallest} lb");
60
    Console.WriteLine($"Average: {average:F1} lb");
61
}
62
else
63
{
64
    Console.WriteLine("Not one bite. Try shallow water next time.");
65
}

Task 4: Break It on Purpose

Three changes, one at a time. Write down exactly what happens, and put each one back before the next.

1. Change totalWeight = totalWeight + weight; to totalWeight = totalWeight + 1; and play a trip. Record the total weight and the average, and say which of the four patterns you accidentally wrote.
2. Put it back. Now start smallest at 0 instead of 999. Record what it reports.
3. Put it back. Change fishCaught > 0 to fishCaught >= 0, then answer 3 on every cast — there is no spot 3, so you are casting onto dry land. Record all five report lines.

Number 1 is the dangerous one, because it runs and looks fine. Say how long it would have taken you to notice if you had not been adding up your fish by hand. For number 3, say which of the five lines are starting values that leaked out, and look up what NaN stands for.

Challenge (Optional): Start From the First Fish

• 999 works until somebody lands a 1,000 lb fish. Rewrite the biggest and the smallest so they start from the first fish instead of from a guess.
• The first fish is the special one, and you already have a variable that tells you how many fish you have caught.
• Add a comment explaining why this version cannot be broken by an unusual catch.

Checkpoint

One real trip from the finished program. Your fish will be different, but your report has to agree with your fish.

Ten casts. Shallow water bites often. Deep water bites less, but bigger.

Cast 1: shallow (1) or deep (2)? 1 [Enter]
  A 5 lb fish!
Cast 2: shallow (1) or deep (2)? 1 [Enter]
  A 2 lb fish!
Cast 3: shallow (1) or deep (2)? 2 [Enter]
  Nothing bites.
Cast 4: shallow (1) or deep (2)? 1 [Enter]
  A 2 lb fish!
Cast 5: shallow (1) or deep (2)? 2 [Enter]
  Nothing bites.
Cast 6: shallow (1) or deep (2)? 2 [Enter]
  Nothing bites.
Cast 7: shallow (1) or deep (2)? 1 [Enter]
  Nothing bites.
Cast 8: shallow (1) or deep (2)? 1 [Enter]
  A 2 lb fish!
Cast 9: shallow (1) or deep (2)? 2 [Enter]
  Nothing bites.
Cast 10: shallow (1) or deep (2)? 1 [Enter]
  A 1 lb fish!

Total weight: 12 lb
Fish caught: 5 of 10
Biggest: 5 lb
Smallest: 1 lb
Average: 2.4 lb

• Your total weight matches your fish added up by hand
• Your average has real decimals. 12 ÷ 5 is 2.4; if it reads 2.0 the division is still whole-number
• You recorded both trip totals from Task 1, and one wrong and one right average from Task 3
• All three Task 4 results are recorded

Reflection

Answer the following questions before submitting your work.

1. An accumulator and a counter look almost identical in code. Explain the difference, and give a question that each one answers about the same fishing trip.
2. Starting biggest at 0 is safe in your fishing game, but it was a bug on the deck's temperature readings. Explain what is different about the data, and why a bug that only appears on some data is hard to catch.
3. Before you changed fishCaught to a double, your average printed with a .0 on the end, and that looks like a properly formatted answer. Explain what C# actually did, and why :F1 could not have rescued it.

Submit

Submit four things to the dropbox:

1. Your 1-20-fishing-trip program file.
2. Your two Task 1 trip totals, and one wrong and one right average from Task 3.
3. All three Task 4 results — including which pattern number 1 turned into, and the five report lines from dry land.
4. Your three reflection answers.

Activity Complete