> Vectors are Jitzu's dynamic arrays — create, access, iterate, and transform collections of values.

# Vectors

Vectors are dynamic arrays that can grow at runtime. They are the primary collection type in Jitzu.

## Creating Vectors

```jitzu
// Initialize with values
let numbers = [1, 2, 3, 4, 5]
let names = ["Alice", "Bob", "Charlie"]

// Empty typed vector
let scores = Double[]

// Explicit type annotation
let ages: Int[] = [25, 30, 35]
```

## Accessing Elements

```jitzu
let colors = ["red", "green", "blue"]

// Index from the start (0-based)
print(colors[0])   // "red"
print(colors[1])   // "green"
print(colors[2])   // "blue"

// Negative indexing (from the end)
print(colors[-1])  // "blue"
print(colors[-2])  // "green"
```

## Adding Elements

```jitzu
let items = [1, 2, 3]

// push appends to the end
items.push(4)
items.push(5)
print(items)  // [1, 2, 3, 4, 5]
```

## Length

```jitzu
let items = [10, 20, 30]
print(items.length)  // 3
```

## Iterating

```jitzu
let fruits = ["apple", "banana", "cherry"]

// for-in loop
for fruit in fruits {
    print(\`I like {fruit}\`)
}

// With index using a range
for i in 0..fruits.length {
    print(\`{i}: {fruits[i]}\`)
}
```

## Safe Indexing

Indexing a vector returns an `Option` — out-of-bounds access returns `None` instead of crashing:

```jitzu
let items = [10, 20, 30]

match items[5] {
    Some(value) => print(value),
    None => print("Index out of bounds"),
}
```

## Mixed-Type Vectors

Vectors can hold mixed types when needed:

```jitzu
let things = [1, 'a', false, "hello"]
things.push(3.14)
print(things)
```

## Common Patterns

### Building a vector in a loop

```jitzu
let squares = Int[]
for i in 1..=10 {
    squares.push(i ** 2)
}
print(squares)  // [1, 4, 9, 16, 25, 36, 49, 64, 81, 100]
```

### Checking if a vector is empty

```jitzu
let items = Int[]

if items.length == 0 {
    print("No items yet")
}
```

Vectors are Jitzu's workhorse collection. Next, explore [Dates](/docs/language/dates) for working with dates and times.