如何在excel列中创建字母

Question

我尝试创建一个字母系列，例如 a,b,c,...z,aa,ab,ac,ad,ae,af,...,az,ba,bb,bc,...,bz,..zz,aaa,aab,aac..up to given number(N)

但是当我尝试使用for loops 创建它时，我在元素中的每个第二个字符创建了一个for loop 这意味着打印 a..z - loop1, aafor each second letter like a ，我写了一个新的for循环

是否可以使用 for 循环创建这种类型系列...

提前谢谢...

Answer 1

这是怎么做的：

    public static string GetExcelColumnName(int index)
    {
        int d = index;
        string name = "";
        int mod;

        while (d > 0)
        {
            mod = (d - 1) % 26;
            name = Convert.ToChar('a' + mod).ToString() + name;
            d = (int)((d - mod) / 26);
        }

        return name;
    }

    public static IEnumerable<string> GetExcelColumns(int n) {
        for (int i = 1; i <= n; i++)
        {
            yield return GetExcelColumnName(i);
        }
    }

    static void Main(string[] args)
    {
        int i = 1;
        foreach (var item in GetExcelColumns(900))
        {
            Console.Write(i++ + ": " + item + " ");
        }
        Console.WriteLine();
    }

---

GetExcelColumnName的解释：

//Suppose index = 1, `GetExcelColumnName` should return `"a"`.
    d = 1
    d > 0
        mod = (d - 1) % 26; //mod now is 0
        Convert.ToChar('a' + mod); // => That's 'a'
        //name now is "a"
        d = (d - mod) / 26 = (1 - 0) / 26 = 0 // d is now 0
    //End of While
    method returns "a"

//Suppose index = 28, `GetExcelColumnName` should return `"ab"`.
    d = 28
    d > 0
        mod = (d - 1) % 26; //mod now is 1 (27 modulo 26)
        Convert.ToChar('a' + mod); // => That's 'b'
        //name now is "b"
        d = (d - mod) / 26 = (28 - 1) / 26 = 1 // d is now 1
    d > 0
        mod = (d - 1) % 26; //mod now is 0 (0 modulo 26)
        Convert.ToChar('a' + mod); // => That's 'a'
        //name now is "ab"
        d = (d - mod) / 26 = (1 - 0) / 26 = 0 // d is now 0
    //End of While
    method returns "ab"

Answer 2

这对于列表和推导非常简单

例如在python中

alpha = ['a','b','c','d','e','f','g','h','i']

def merge(x,y):
    new = [ a+b for a in x for b in y]
    return new 

print(merge(alpha,alpha))
print(merge(alpha,merge(alpha,alpha)))

会给你你想要的。在 C# 中，您可以找到等效的（或在 F# 中）

Answer 3

我认为正确看待这个问题的方法是，以 27 为底的数字，并用 0 跳过所有数字。您的数字是 _abcdefghijklmnopqrstuvwxyz（_ 的值为 0，z 的值为 26），然后您创建基数为 27 的数字是这样的：

nums_generated = 0
next_num = 1
while nums_generated < N:
   number_string = generate_base_27(next_num)
   if not '_' in number_string:
       print number_string
       num_generated = num_generated + 1
   next_num = next_num + 1

这应该可以解决问题。要使用给定字符集创建以 27 为基数的数字，请查找例如 here ，并根据需要以 27 为基数进行适当的更正。