Dictionaries in Visual Basic

Key-value stores with TryGetValue, the lookup that cannot throw.

Dim stock As New Dictionary(Of String, Integer) From {
    {"flour", 12}, {"sugar", 5}
}
stock("yeast") = 9
stock("sugar") += 3

If stock.ContainsKey("flour") Then Console.WriteLine("flour on hand")

Dim salt As Integer
If Not stock.TryGetValue("salt", salt) Then salt = 0
Console.WriteLine($"salt jars: {salt}")

For Each pair In stock
    Console.WriteLine($"{pair.Key,-8} {pair.Value,3}")
Next

How it works

1. From {{...}} pairs keys with values at construction.
2. Assigning to a missing key adds it; += updates in place.
3. TryGetValue fills a variable and reports success as Boolean.
4. For Each pair walks KeyValuePairs with .Key and .Value.

Keywords and builtins used here

• Dim
• Each
• For
• If
• Integer
• New
• Next
• Not
• Of
• String
• Then

The run, in numbers

Lines

15

Characters to type

388

Tokens

107

Three-star pace

85 tpm

At the three-star pace of 85 tokens a minute, this run takes about 76 seconds.

Type this snippet

Step 3 of 3 in Collections, step 6 of 29 in Language basics.

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Dictionaries in other languages

• C#