Question

我是C＃的新手。我有一个简短的表单和一个长形式的客户端代码。短格式是一些字母字符和一些数字字符（ABC12），而长格式总是15个字符长，alpha和数字部分之间的空格用零填充（ABC000000000012）。我需要能够从短格式转换为长格式。下面的代码就是我如何使用它 - 这是最好的方法吗？

public string ExpandCode(string s)
{
    // s = "ABC12"
    int i = 0;
    char c;
    bool foundDigit = false;
    string o = null;

    while (foundDigit == false)
    {
        c = Convert.ToChar(s.Substring(i, 1));
        if (Char.IsDigit(c))  
        {
            foundDigit = true;
            o = s.Substring(0, i) + new String('0', 15-s.Length) + s.Substring(i,s.Length-i); 
        }
        i += 1;
    }
    return (o); //o = "ABC000000000012"
}

Answer 1

您的代码基本上是正确的，但它可能很慢，因为String.Substring(...)每次调用时都会创建一个新字符串。

我还建议你使用.NET API的内置函数来完成你的任务，这可以使编码更容易：

private char[] numbers = new char[]{'1', '2', '3', '4', '5', '6', '7', '8', '9', '0'};

public string ExpandCode(string s)
{
    //Find the first numeric char.
    int index = s.IndexOfAny(numbers);
    //Insert zeros and return the result. 
    return s.Insert(index, new String('0', 15 - s.Length));
}

Answer 2

看看这个：

public string ExpandCode(string s)
{
    var builder = new StringBuilder(s);
    var index = Array.FindIndex(s.ToArray(), x => char.IsDigit(x));

    while (builder.Length < 15)
    {
        builder.Insert(index, '0');
    }

    return builder.ToString();
}

我认为字符串总是字母 - ＆gt;数字（如“abc123”或“ab1234”）。

Answer 3

更纯净，更快

public static string ExpandCode4(string s)
{
    char[] res = new char[15];
    int ind = 0;
    for (int i = 0; i < s.Length && s[i] >= 'A'; i++)
        res[ind++] = s[i];
    int tillDigit = ind;
    for (int i = 0; i < 15 - s.Length; i++)
        res[ind++] = '0';
    for (int i = 0; i < s.Length - tillDigit; i++)
        res[ind++] = s[tillDigit + i];
    return new string(res);
}

所有答案的基准如下，

internal class Program
{
    private static void Main(string[] args)
    {
        var inputs = new List<string>();
        for (int i = 0; i < 10000000; i++)
        {
            inputs.Add("ABC1234");
        }

        var n1 = DateTime.Now;
        inputs.ForEach(i => ExpandCode1(i));
        var r1 = (DateTime.Now - n1).Ticks;

        var n2 = DateTime.Now;
        inputs.ForEach(i => ExpandCode2(i));
        var r2 = (DateTime.Now - n2).Ticks;

        var n3 = DateTime.Now;
        inputs.ForEach(i => ExpandCode3(i));
        var r3 = (DateTime.Now - n3).Ticks;

        var n4 = DateTime.Now;
        inputs.ForEach(i => ExpandCode4(i));
        var r4 = (DateTime.Now - n4).Ticks;

        var results = new List<Result>()
        {
            new Result() {Name = "1", Ticks = r1},
            new Result() {Name = "2", Ticks = r2},
            new Result() {Name = "3", Ticks = r3},
            new Result() {Name = "4", Ticks = r4}
        };
        results.OrderBy(r => r.Ticks).ToList().ForEach(Console.WriteLine);
        Console.ReadKey();
    }

    public static string ExpandCode4(string s)
    {
        char[] res = new char[15];
        int ind = 0;
        for (int i = 0; i < s.Length && s[i] >= 'A'; i++)
            res[ind++] = s[i];
        int tillDigit = ind;
        for (int i = 0; i < 15 - s.Length; i++)
            res[ind++] = '0';
        for (int i = 0; i < s.Length - tillDigit; i++)
            res[ind++] = s[tillDigit + i];
        return new string(res);
    }
    public static string ExpandCode1(string s)
    {
        char[] numbers = new char[] { '1', '2', '3', '4', '5', '6', '7', '8', '9', '0' };
        //Find the first numeric char.
        int index = s.IndexOfAny(numbers);
        //Insert zeros and return the result. 
        return s.Insert(index, new String('0', 15 - s.Length));
    }

    public static string ExpandCode2(string s)
    {
        var builder = new StringBuilder(s);
        var index = Array.FindIndex(s.ToArray(), x => char.IsDigit(x));

        while (builder.Length < 15)
        {
            builder.Insert(index, '0');
        }

        return builder.ToString();
    }

    public static string ExpandCode3(string s)
    {
        var match = Regex.Match(s, @"([^\d]+)(\d+)");
        var letters = match.Groups[1].Value;
        var numbers = int.Parse(match.Groups[2].Value);
        var formatString = "{0}{1:d" + (15 - letters.Length) + "}";
        var longForm = string.Format(formatString, letters, numbers);
        return longForm;
    }

}
public class Result
{
    public long Ticks { get; set; }
    public string Name { get; set; }
    public override string ToString()
    {
        return Name + " - " + Ticks;
    }
}

Answer 4

您可以使用string.Format（）来为您处理填充。我使用正则表达式（而不是以非常强大的方式）来解析字母和数字，但是你可以用另一种方式更有效地做到这一点。

关键是我们动态计算出我们需要多少零，然后使用格式为X:dY的格式字符串，其中X =格式序数，Y =您希望填充的零个数。< / p>

var match = Regex.Match("ABC12", @"([^\d]+)(\d+)");
var letters = match.Groups[1].Value;
var numbers = int.Parse(match.Groups[2].Value);
var formatString = "{0}{1:d" + (15 - letters.Length) + "}";
var longForm = string.Format(formatString, letters, numbers);

如何将字符插入字母数字字符串

4 个答案: