在 C# 中，将字符串从数字 0-9 递增到小写 a-z 再到大写 A-Z

这使用问题"在 .NET 中将基数 10 的数字转换为任何基数的最快方法？"中支持任意基数的IntToString，但硬编码为使用您的格式（即基数 62）。

private static readonly char[] baseChars = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ".ToCharArray();
private const long targetBase = 62;
private const long maxNum = 62L*62*62*62*62*62 - 1;
public static string NumberToString(long value)
{
    if (value > maxNum)
        throw new ArgumentException();
    char[] result = "000000".ToCharArray();
    int i = result.Length - 1;
    do
    {
        result[i--] = baseChars[value % targetBase];
        value /= targetBase;
    } 
    while (value > 0);
    return new string(result);
}

一种基于字符串的方法，类似于 Tim S 的答案：

private static string Increment(string input)
    {
        var myChars = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ".ToCharArray();
        var array = input.ToCharArray();
        for (int i = array.Count()-1; i >= 0; i--)
        {
            int newValue = (Array.IndexOf(myChars, array[i]) + 1) % 62;
            array[i] = myChars[newValue];
            if (newValue != 0)
                break;
        }
        return new string(array);
    }

这是另一种方法...它允许您传入"起始修订"（示例中为"000000"）。 我最初是在很久以前 VB.Net 写的，是为了回答一个有非常具体要求的问题......因此，以下可能不是最有效的做事方式。

public partial class Form1 : Form
{
    private Revision rev;
    public Form1()
    {
        InitializeComponent();
        Reset();
    }
    private void Reset()
    {
        rev = new Revision("0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ", "000000");
        label1.Text = rev.CurrentRevision;
    }
    private void btnReset_Click(object sender, EventArgs e)
    {
        Reset();
    }
    private void btnNext_Click(object sender, EventArgs e)
    {
        rev.NextRevision();
        if (rev.CurrentRevision.Length == 7)
        {
            MessageBox.Show("Sequence Complete");
            Reset();
        }
        else
        {
            label1.Text = rev.CurrentRevision;
        }
    }
}
public class Revision
{
    private string chars;
    private char[] values;
    private System.Text.StringBuilder curRevision;
    public Revision()
    {
        this.DefaultRevision();
    }
    public Revision(string validChars)
    {
        if (validChars.Length > 0)
        {
            chars = validChars;
            values = validChars.ToCharArray();
            curRevision = new System.Text.StringBuilder(values[0]);
        }
        else
        {
            this.DefaultRevision();
        }
    }
    public Revision(string validChars, string startingRevision)
        : this(validChars)
    {
        curRevision = new System.Text.StringBuilder(startingRevision);
        int i = 0;
        for (i = 0; i <= curRevision.Length - 1; i++)
        {
            if (Array.IndexOf(values, curRevision[i]) == -1)
            {
                curRevision = new System.Text.StringBuilder(values[0]);
                break;
            }
        }
    }
    private void DefaultRevision()
    {
        chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        values = chars.ToCharArray();
        curRevision = new System.Text.StringBuilder(values[0]);
    }
    public string ValidChars
    {
        get { return chars; }
    }
    public string CurrentRevision
    {
        get { return curRevision.ToString(); }
    }
    public string NextRevision(int numRevisions = 1)
    {
        bool forward = (numRevisions > 0);
        numRevisions = Math.Abs(numRevisions);
        int i = 0;
        for (i = 1; i <= numRevisions; i++)
        {
            if (forward)
            {
                this.Increment();
            }
            else
            {
                this.Decrement();
            }
        }
        return this.CurrentRevision;
    }
    private void Increment()
    {
        char curChar = curRevision[curRevision.Length - 1];
        int index = Array.IndexOf(values, curChar);
        if (index < (chars.Length - 1))
        {
            index = index + 1;
            curRevision[curRevision.Length - 1] = values[index];
        }
        else
        {
            curRevision[curRevision.Length - 1] = values[0];
            int i = 0;
            int startPosition = curRevision.Length - 2;
            for (i = startPosition; i >= 0; i += -1)
            {
                curChar = curRevision[i];
                index = Array.IndexOf(values, curChar);
                if (index < (values.Length - 1))
                {
                    index = index + 1;
                    curRevision[i] = values[index];
                    return;
                }
                else
                {
                    curRevision[i] = values[0];
                }
            }
            curRevision.Insert(0, values[0]);
        }
    }
    private void Decrement()
    {
        char curChar = curRevision[curRevision.Length - 1];
        int index = Array.IndexOf(values, curChar);
        if (index > 0)
        {
            index = index - 1;
            curRevision[curRevision.Length - 1] = values[index];
        }
        else
        {
            curRevision[curRevision.Length - 1] = values[values.Length - 1];
            int i = 0;
            int startPosition = curRevision.Length - 2;
            for (i = startPosition; i >= 0; i += -1)
            {
                curChar = curRevision[i];
                index = Array.IndexOf(values, curChar);
                if (index > 0)
                {
                    index = index - 1;
                    curRevision[i] = values[index];
                    return;
                }
                else
                {
                    curRevision[i] = values[values.Length - 1];
                }
            }
            curRevision.Remove(0, 1);
            if (curRevision.Length == 0)
            {
                curRevision.Insert(0, values[0]);
            }
        }
    }
}