C# 字符串操作：常用方法汇总（含案例）

public class StringHelper
{
    // 拼接字符串（比+号高效）
    public static string JoinStrings(params string[] parts)
    {
        return string.Join("-", parts);
    }
    // 截取字符串
    public static string Substring(string str, int startIndex, int length)
    {
        if (string.IsNullOrEmpty(str)) return "";
        return str.Substring(startIndex, Math.Min(length, str.Length - startIndex));
    }
    // 替换字符串
    public static string ReplaceKeyword(string str, string keyword, string replacement)
    {
        return str.Replace(keyword, replacement);
    }
    // 判断字符串是否包含关键词
    public static bool ContainsKeyword(string str, string keyword)
    {
        return !string.IsNullOrEmpty(str) && str.Contains(keyword);
    }
}
// 调用示例
string joined = StringHelper.JoinStrings("2024", "01", "08");
Console.WriteLine("拼接结果：" + joined); // 输出：2024-01-08
string sub = StringHelper.Substring("C#编程教程", 2, 3);
Console.WriteLine("截取结果：" + sub); // 输出：编程教
string replaced = StringHelper.ReplaceKeyword("C#很难", "难", "简单");
Console.WriteLine("替换结果：" + replaced); // 输出：C#很简单
bool hasCSharp = StringHelper.ContainsKeyword("学习C#", "C#");
Console.WriteLine("是否包含C#：" + hasCSharp); // 输出：True