Maps in Go

What is a Go Map?

A map is a built-in data structure that associates values with unique keys. It provides fast lookups, additions, and deletions.

Declaration & Initialization

Maps can be created using the make function or a map literal:

scores := make(map[string]int)
capitals := map[string]string{"Japan": "Tokyo", "France": "Paris"}

Key Characteristics

• Unordered collection
• Fast lookups (O(1) average time complexity)
• Keys must be comparable (cannot use slices, maps, or functions as keys)
• Maps are reference types (passing a map to a function passes a reference)

Common Operations

Add or update: m["key"] = value

Retrieve: value = m["key"]

Delete: delete(m, "key")

Check existence: value, exists := m["key"]

Concurrency Note

Maps in Go are not safe for concurrent use. When multiple goroutines access a map, you must use synchronization mechanisms like sync.Mutex.