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

试试这个:

static public string UpperCaseFirstCharacter(this string text) {
    return Regex.Replace(text, "^[a-z]", m => m.Value.ToUpper());
}

2012-08-15 17:39:37

其他回答

当你所需要的只是:

/// <summary>
/// Returns the input string with the first character converted to uppercase if a letter
/// </summary>
/// <remarks>Null input returns null</remarks>
public static string FirstLetterToUpperCase(this string s)
{
    if (string.IsNullOrWhiteSpace(s))
        return s;

    return char.ToUpper(s[0]) + s.Substring(1);
}

值得注意的点:

这是一个扩展方法。如果输入是空的、空的或空白的，则输入按原样返回。字符串。IsNullOrWhiteSpace是在. net Framework 4中引入的。这将不适用于旧的框架。

2014-11-02 14:57:03

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

我认为下面的方法是最好的解决方案。

class Program
{
    static string UppercaseWords(string value)
    {
        char[] array = value.ToCharArray();
        // Handle the first letter in the string.
        if (array.Length >= 1)
        {
            if (char.IsLower(array[0]))
            {
                array[0] = char.ToUpper(array[0]);
            }
        }
        // Scan through the letters, checking for spaces.
        // ... Uppercase the lowercase letters following spaces.
        for (int i = 1; i < array.Length; i++)
        {
            if (array[i - 1] == ' ')
            {
                if (char.IsLower(array[i]))
                {
                    array[i] = char.ToUpper(array[i]);
                }
            }
        }
        return new string(array);
    }

    static void Main()
    {
        // Uppercase words in these strings.
        const string value1 = "something in the way";
        const string value2 = "dot net PERLS";
        const string value3 = "String_two;three";
        const string value4 = " sam";
        // ... Compute the uppercase strings.
        Console.WriteLine(UppercaseWords(value1));
        Console.WriteLine(UppercaseWords(value2));
        Console.WriteLine(UppercaseWords(value3));
        Console.WriteLine(UppercaseWords(value4));
    }
}

Output

Something In The Way
Dot Net PERLS
String_two;three
 Sam

参考

2018-10-29 00:45:48

string emp="TENDULKAR";
string output;
output=emp.First().ToString().ToUpper() + String.Join("", emp.Skip(1)).ToLower();

2013-05-02 11:47:14

FluentSharp有lowerCaseFirstLetter方法来做这个。

2015-07-21 17:25:20

使字符串的第一个字母大写(以最大性能)

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