jellyfin/MediaBrowser.Model/Extensions/StringHelper.cs

using System;

namespace MediaBrowser.Model.Extensions
{
    /// <summary>
    /// Helper methods for manipulating strings.
    /// </summary>
    public static class StringHelper
    {
        /// <summary>
        /// Returns the string with the first character as uppercase.
        /// </summary>
        /// <param name="str">The input string.</param>
        /// <returns>The string with the first character as uppercase.</returns>
        public static string FirstToUpper(string str)
        {
            if (str.Length == 0)
            {
                return str;
            }

            // We check IsLower instead of IsUpper because both return false for non-letters
            if (!char.IsLower(str[0]))
            {
                return str;
            }

            return string.Create(
                str.Length,
                str.AsSpan(),
                (chars, buf) =>
                {
                    chars[0] = char.ToUpperInvariant(buf[0]);
                    buf.Slice(1).CopyTo(chars.Slice(1));
                });
        }
    }
}