Maps and Hashing

13. Maps and Hashing

var ages map[string]int       // Declare a map with string keys and int values

You can also create a map using a map literal.

colors := map[string]string{
    "red":   "#FF0000",
    "green": "#00FF00",
    "blue":  "#0000FF",
}

Accessing and Modifying Map Elements:

You can access and modify map elements using their keys.

colors["red"] = "#FF3333"       // Modify the value of the "red" key
value := colors["green"]       // Access the value of the "green" key

Checking for Existence:

You can use the existence check to determine if a key exists in the map.

color, exists := colors["yellow"]
if exists {
    fmt.Println("Value:", color)
} else {
    fmt.Println("Key does not exist.")
}

Deleting Map Elements:

Use the 'delete' function to remove a key-value pair from a map.

delete(colors, "blue")             // Delete the "blue" key and its value

Iterating Over Maps:

Use a 'for'loop to iterate over the keys and values of a map.

for key, value := range colors {
    fmt.Printf("Key: %s, Value: %s\n", key, value)
}

Hashing:

Hashing is a fundamental concept used in maps to efficiently organize and access key-value pairs. A hash function takes a key and produces a hash code, which is used to index and locate the value associated with that key.

Hash Collisions:

Hash collisions occur when two different keys produce the same hash code. Go's map implementation uses open addressing and separate chaining to handle collisions.

Summary:

• Maps are unordered collections of key-value pairs.
• Hashing is used to efficiently locate values based on keys.
• Maps are declared using the 'map' keyword.
• Use the 'delete' function to remove elements from a map.
• Iterate over maps using 'for range'.

Understanding maps and hashing is essential for building efficient and scalable programs in Go. Maps provide a versatile way to store and retrieve data based on unique keys, while hashing ensures quick access to values without relying on linear searches.