如何根据用户输入的密码长度变量循环调用随机字符生成子程序？

Hey there! Let's sort out your password generator code so it properly gets the user's desired length and loops to build the password. Here's how to fix and enhance your existing code:

问题分析 #

First, let's look at the gaps in your current code:

• The n variable from inp() is a string (since Console.ReadLine() returns a string), but we need an integer to control the loop.
• Calling Randomize() every time in randi() can lead to less random results—it should only run once at the start of your program to properly seed the generator.
• The randi() sub doesn't actually return a random character, just sets an index i; we need to map that index to your character library and output the character.
• There's no validation for the user's input (e.g., ensuring it's a number between 1 and 20).

解决方案 #

Let's rewrite and integrate your code step by step:

1. Fix User Input Handling #

Modify the input sub to convert the user's input to an integer, add validation, and ensure it's within the allowed range:

' Global variables (or pass them between subs if you prefer)
Dim n As Integer
' Example character library—adjust this to include/exclude characters as needed
Dim charLibrary As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789!@#$%^&*()"

Public Sub GetPasswordLength()
    Dim input As String
    Do
        Console.WriteLine("How many characters do you want in your password? (1-20 allowed)")
        input = Console.ReadLine()
        ' Try to convert input to integer and check if it's in valid range
        If Integer.TryParse(input, n) AndAlso n >= 1 AndAlso n <= 20 Then
            Exit Do ' Valid input, exit loop
        Else
            Console.WriteLine("Invalid input! Please enter a number between 1 and 20.")
        End If
    Loop
End Sub

2. Optimize Random Character Generation #

Move Randomize() to the start of your program, and change randi() to a function that returns a single random character from your library:

Public Function GetRandomCharacter() As Char
    ' Calculate a valid index within the character library bounds
    Dim randomIndex As Integer = CInt(Rnd() * (charLibrary.Length - 1))
    Return charLibrary(randomIndex)
End Function

3. Integrate the Loop to Build the Password #

Create a main sub that ties everything together:

Sub Main()
    Randomize() ' Initialize random generator ONCE at program start
    GetPasswordLength() ' Get valid length from user
    
    Dim password As String = ""
    ' Loop n times to append random characters to the password
    For i As Integer = 1 To n
        password &= GetRandomCharacter()
    Next
    
    Console.WriteLine($"Your generated password is: {password}")
    Console.ReadLine() ' Keep console open to view the result
End Sub

Key Notes #

• Input Validation: The Do...Loop ensures the user can't proceed until they enter a valid number in the 1-20 range.
• Randomness: Calling Randomize() once at the start ensures the random generator is properly seeded for more reliable random results.
• Customization: Adjust the charLibrary string to include any symbols, letters, or numbers you want in your passwords.

内容的提问来源于stack exchange，提问作者It was me DIO