# IB computer science HL October 11 2016 Lesson Notes

## What are we going to learn today?

1. Today in class we will start learning about collections and arrays. THESE ARE DIFFERENT.
2. If using weapons as array examples offends you, please use this potion list as an alternative.
```<?php

# this file is used to teach the VERY BASICS of arrays in PHP

\$shop_items = array(
"short sword",
"dagger",
"flail",
"morning star",
"spear",
"long bow",
"crossbow",
"long sword",
"two handed sword",
"scimitar",
"short bow",
"staff",
"club"
);

# This creates a very simple array.
# We can perform some different operations on this array:

# count the items in the array:

echo "<p>Welcome to our shop. We sell many things for adventurers </p>";
echo "<p>==========================================</p>";

# let's list our inventory:

for (\$i = 0; \$i < count(\$shop_items); \$i++)
{

echo \$i  . " - \$shop_items[\$i] <br />";

}
?>
```

Below we have an example if an associative array:

```<?php

# this file is used to teach the VERY BASICS of arrays in PHP

\$shop_items = array(
"short sword" =>"10",
"dagger" => "2",
"flail" => "12",
"morning star" => "15",
"spear" => "25",
"long bow" => "15",
"crossbow" => "20",
"long sword" => "21",
"two handed sword" => "30",
"scimitar" => "18",
"short bow" => "15",
"staff" => "5",
"club" => "2"
);

# This creates a very simple array.
# We can perform some different operations on this array:

# count the items in the array:

echo "<p>Welcome to our shop. We sell many things for adventurers </p>";
echo "<p>==========================================</p>";

# let's list our inventory:

foreach (\$shop_items as \$i => \$cost_of_item)
{

echo \$i  . " costs \$cost_of_item <br />";

}
?>
```

## How am I being assessed today?

1. You will be formatively assessed in class today

## As a computer scientist, you have:

• Confidence in dealing with complexity
• Persistence in working with difficult problems
• Tolerance for ambiguity
• The ability to deal with open-ended problems
• The ability to communicate and work with others to achieve a common goal or solution