使字符串的第一个字母大写(以最大性能)

我有一个带有文本框的DetailsView 我希望输入的数据总是以大写的第一个字母保存。

例子:

"red" --> "Red"
"red house" --> " Red house"

我怎样才能实现性能最大化呢?

注意:

Based on the answers and the comments under the answers, many people think this is asking about capitalizing all words in the string. E.g. => Red House It isn't, but if that is what you seek, look for one of the answers that uses TextInfo's ToTitleCase method. (Note: Those answers are incorrect for the question actually asked.) See TextInfo.ToTitleCase documentation for caveats (doesn't touch all-caps words - they are considered acronyms; may lowercase letters in middle of words that "shouldn't" be lowered, e.g., "McDonald" → "Mcdonald"; not guaranteed to handle all culture-specific subtleties re capitalization rules.)

注意:

第一个字母之后的字母是否必须小写，这个问题很模糊。公认的答案假定只有第一个字母需要修改。如果要强制字符串中除第一个字母外的所有字母都小写，请查找包含ToLower且不包含ToTitleCase的答案。

当前回答

最简单和最快的方法是将字符串的第一个字符替换为大写字符:

string str = "test";<br>
str = str.Replace(str[0], char.ToUpper(str[0]));

2013-09-19 10:40:05

其他回答

这也可以使用Take, Skip和Aggregate:

    public static string FirstCharToUpper(this string text) 
    {
      if (String.IsNullOrEmpty(text)) return String.Empty;
      var first = text.Take(1).ToArray()[0].ToString().ToUpper();
      var rest = text.Skip(1).Aggregate("", ((xs, x) => xs + x));
      return first + rest;
    }

2022-08-25 12:55:11

你可以使用“ToTitleCase方法”:

string s = new CultureInfo("en-US").TextInfo.ToTitleCase("red house");
//result : Red House

这种扩展方法解决了所有标题问题。

使用简单:

string str = "red house";
str.ToTitleCase();
//result : Red house

string str = "red house";
str.ToTitleCase(TitleCase.All);
//result : Red House

扩展方法:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Globalization;

namespace Test
{
    public static class StringHelper
    {
        private static CultureInfo ci = new CultureInfo("en-US");
        //Convert all first latter
        public static string ToTitleCase(this string str)
        {
            str = str.ToLower();
            var strArray = str.Split(' ');
            if (strArray.Length > 1)
            {
                strArray[0] = ci.TextInfo.ToTitleCase(strArray[0]);
                return string.Join(" ", strArray);
            }
            return ci.TextInfo.ToTitleCase(str);
        }

        public static string ToTitleCase(this string str, TitleCase tcase)
        {
            str = str.ToLower();
            switch (tcase)
            {
                case TitleCase.First:
                    var strArray = str.Split(' ');
                    if (strArray.Length > 1)
                    {
                        strArray[0] = ci.TextInfo.ToTitleCase(strArray[0]);
                        return string.Join(" ", strArray);
                    }
                    break;
                case TitleCase.All:
                    return ci.TextInfo.ToTitleCase(str);
                default:
                    break;
            }
            return ci.TextInfo.ToTitleCase(str);
        }
    }

    public enum TitleCase
    {
        First,
        All
    }
}

2013-04-06 12:30:46

正如BobBeechey在回答这个问题时所建议的，下面的代码可以解决这个问题:

private void txt_fname_TextChanged(object sender, EventArgs e)
{
    char[] c = txt_fname.Text.ToCharArray();
    int j;
    for (j = 0; j < txt_fname.Text.Length; j++)
    {
        if (j==0) c[j]=c[j].ToString().ToUpper()[0];
        else c[j] = c[j].ToString().ToLower()[0];
    }
    txt_fname.Text = new string(c); 
    txt_fname.Select(txt_fname.Text.Length, 1);
}

2012-08-16 21:33:55

string s_Val = "test";
if (s_Val != "")
{
   s_Val  = char.ToUpper(s_Val[0]);
   if (s_Val.Length > 1)
   {
      s_Val += s_Val.Substring(1);
   }
 }

2010-11-09 15:27:04

public static string ToInvarianTitleCase(this string self)
{
    if (string.IsNullOrWhiteSpace(self))
    {
        return self;
    }

    return CultureInfo.InvariantCulture.TextInfo.ToTitleCase(self);
}

2014-05-11 03:00:10

使字符串的第一个字母大写(以最大性能)

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