How Can You Initialize an Array in Go Efficiently Without Loops?

Efficient Array Initialization in Go without Loops

Initialising an array with a uniform value can be done using conventional for loops. However, for large arrays, this approach becomes inefficient. This article explores alternative methods to initialise an array without using loops.

The Traditional Approach

The conventional method involves iterating over the elements of the array using a for loop and setting each element to the desired value.

<code class="go">var A [n]bool
for i := 0; i < n; i++ {
    A[i] = true
}</code>

Alternate Approaches

• Composite Literals:
  Composite literals allow the creation and initialisation of slices or arrays, but they are not shorter than the traditional approach.

<code class="go">b1 := []bool{true, true, true}
b2 := [3]bool{true, true, true}</code>

• Constant for True Value:
  Introducing a constant for the true value can slightly reduce the code length.

<code class="go">const T = true
b3 := []bool{T, T, T}</code>

• Negated Values Storage:
  Depending on the application logic, it may be more efficient to store the negated values instead. This way, the all-false zero value becomes a suitable initialisation.

<code class="go">presents := []bool{true, true, true, true, true, true}

// Is equivalent to:

missings := make([]bool, 6) // All false
// missings=false means not missing (i.e., present)</code>

• Memset Operation:
  Filling an array with a specific value is referred to as a "memset" operation. Go does not provide a built-in function for this, but efficient solutions can be found in other sources.

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