TheAlgorithms/Go · error

size must be greater than 0

Error message

size must be greater than 0

What it means

NewCircularQueue allocates a fixed-size ring buffer; it refuses to construct a queue with a non-positive capacity since a zero or negative capacity cannot store any items and would break the modulo arithmetic of the ring. The library returns this error instead of panicking on make([]T, size).

Source

Thrown at structure/circularqueue/circularqueuearray.go:31

// errors package: Provides functions to create and manipulate error values
import (
	"errors"
)

// CircularQueue represents a circular queue data structure.
type CircularQueue[T any] struct {
	items []T
	front int
	rear  int
	size  int
}

// NewCircularQueue creates a new CircularQueue with the given size.
// Returns an error if the size is less than or equal to 0.
func NewCircularQueue[T any](size int) (*CircularQueue[T], error) {
	if size <= 0 {
		return nil, errors.New("size must be greater than 0")
	}
	return &CircularQueue[T]{
		items: make([]T, size),
		front: -1,
		rear:  -1,
		size:  size,
	}, nil
}

// Enqueue adds an item to the rear of the queue.
// Returns an error if the queue is full.
func (cq *CircularQueue[T]) Enqueue(item T) error {
	if cq.IsFull() {
		return errors.New("queue is full")
	}
	if cq.IsEmpty() {
		cq.front = 0
	}

View on GitHub (pinned to 5ba447ec5f)

Solutions

1. Ensure the size argument is a positive integer before calling NewCircularQueue
2. Add an explicit check or clamp: if size <= 0 { size = defaultSize }
3. Fix the source of the size value (config, env var, flag) to supply a valid positive number

Example fix

// before
q, err := NewCircularQueue[int](cfg.QueueSize) // cfg.QueueSize == 0
// after
size := cfg.QueueSize
if size <= 0 {
    size = 16 // sensible default
}
q, err := NewCircularQueue[int](size)

func validQueueSize(size int) bool { return size > 0 }
if !validQueueSize(n) { return fmt.Errorf("invalid queue size %d", n) }

q, err := NewCircularQueue[T](n)
if err != nil {
    return fmt.Errorf("queue init: %w", err)
}

When it happens

Trigger: Calling NewCircularQueue[T](0) or NewCircularQueue[T](n) with n < 0, typically when the size comes from an unvalidated config value, user input, or a computed expression that evaluated to zero.

Common situations: Config file with missing or zero capacity field; computing size from a slice length that was empty; default struct values in Go (int zero value) passed straight through without initialization.

Related errors

• queue is full
• queue is empty
• rows have different numbers of columns
• ErrEmptyDequeue
• index out of range

AI-assisted analysis of TheAlgorithms/Go@5ba447ec5f (2026-09-02). Data as JSON: /api/errors/d64558f0e60e4afe. Report an issue: GitHub.