对于第一个字母，带有错误检查:

public string CapitalizeFirstLetter(string s)
{
    if (String.IsNullOrEmpty(s))
        return s;
    if (s.Length == 1)
        return s.ToUpper();
    return s.Remove(1).ToUpper() + s.Substring(1);
}

这是一个方便的扩展

public static string CapitalizeFirstLetter(this string s)
{
    if (String.IsNullOrEmpty(s))
        return s;
    if (s.Length == 1)
        return s.ToUpper();
    return s.Remove(1).ToUpper() + s.Substring(1);
}

我想提供一个“最大性能”的答案。在我看来，“最大性能”的答案抓住了所有的场景，并提供了解释这些场景的问题的答案。所以，这是我的答案。原因如下:

IsNullOrWhiteSpace accounts for strings that are just spaces or null/empty. .Trim() removes white space from the front and back of the string. .First() takes the first element of an IEnumerable<TSource> (or string). We should check to see if it is a letter that can/should be uppercase. We then add the rest of the string, only if the length indicates we should. By .NET best practice, we should provide a culture under System.Globalization.CultureInfo. Providing them as optional parameters makes this method totally reusable, without having to type the chosen culture every time. I also noticed that my and most of these answers did not maintain the whitespace at the beginning of the string. This will also show how to maintain that whitespace. //Capitalize the first letter disregard all chars using regex. public static string RegCapString(this string instring, string culture = "en-US", bool useSystem = false) { if (string.IsNullOrWhiteSpace(instring)) { return instring; } var m = Regex.Match(instring, "[A-Za-z]").Index; return instring.Substring(0, m) + instring[m].ToString().ToUpper(new CultureInfo(culture, useSystem)) + instring.Substring(m + 1); } //Capitalize first char if it is a letter disregard white space. public static string CapString(this string instring, string culture = "en-US", bool useSystem = false) { if (string.IsNullOrWhiteSpace(instring) || !char.IsLetter(instring.Trim().First())) { return instring; } var whiteSpaces = instring.Length - instring.TrimStart().Length; return (new string(' ', whiteSpaces)) + instring.Trim().First().ToString().ToUpper(new CultureInfo(culture, useSystem)) + ((instring.TrimStart().Length > 1) ? instring.Substring(whiteSpaces + 1) : ""); }

对于第一个字母，带有错误检查:

public string CapitalizeFirstLetter(string s)
{
    if (String.IsNullOrEmpty(s))
        return s;
    if (s.Length == 1)
        return s.ToUpper();
    return s.Remove(1).ToUpper() + s.Substring(1);
}

这是一个方便的扩展

public static string CapitalizeFirstLetter(this string s)
{
    if (String.IsNullOrEmpty(s))
        return s;
    if (s.Length == 1)
        return s.ToUpper();
    return s.Remove(1).ToUpper() + s.Substring(1);
}

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。

检查字符串是否为空，将第一个字符转换为大写字母，其余字符转换为小写字母:

public static string FirstCharToUpper(string str)
{
    return str?.First().ToString().ToUpper() + str?.Substring(1).ToLower();
}

下面的函数对所有方式都是正确的:

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);
}

我在这里找到的。