Swift中生成指定区间数值数组的技术实现咨询

Hey there! Let's clean up that array generation part of your Swift function—right now you're using a manual while loop to build the array from m to n, but Swift has built-in, more efficient ways to handle this that are also way easier to read.

The Simplest Fix: Use a Closed Range + Array Initializer #

Instead of manually incrementing a variable and appending to the array, you can directly create an array from a closed range (which includes both the start and end values) with one line of code:

let z = Array(m...n)

This does exactly what your original loop does—generates an array containing every integer from m to n inclusive—but it's:

• More concise: No need to manage extra variables like x or manually append elements
• Safer: Using let instead of var (since you don't need to modify the array right now) prevents accidental changes
• More efficient: Swift's range-to-array conversion is optimized under the hood, better than a hand-written loop for most cases

Updated Full Function #

Here's how your function looks with this optimization:

func step(_ g: Int, _ m: Int, _ n: Int) -> (Int, Int)? { 
    // Generate array of numbers from m to n (inclusive) in one line
    let z = Array(m...n) 
    
    // Your future prime-checking logic can stay/expand here
    for i in z { 
        var k = 2 
        while k < n { 
            if i % k != 0 && i != k { 
                // Add your prime validation logic here later
            } 
            k += 1 
        } 
    } 
    
    print(z) 
    return (0, 0) 
}

Bonus: Skip the Array Entirely (If Possible) #

If you only need to iterate over the numbers from m to n (and don't need to store the entire array for later use), you can skip creating the array entirely and loop directly over the range:

func step(_ g: Int, _ m: Int, _ n: Int) -> (Int, Int)? { 
    // Iterate directly over the range—no array needed!
    for i in m...n { 
        var k = 2 
        while k < n { 
            if i % k != 0 && i != k { 
                // Add your prime validation logic here later
            } 
            k += 1 
        } 
    } 
    
    // If you still need to print the range as an array, you can convert it here
    print(Array(m...n))
    return (0, 0) 
}

This saves memory, especially if n - m is a large number, since you're not storing all the values in an array at once.

内容的提问来源于stack exchange，提问作者user9651872