打开 nuget管理器 搜索 PinYinConverterCore 安装

public static class Helper
{
public static string ToPinYin(this string val, bool first = false) {
            return string.Join("", val.ToCharArray().Select(y => y > 133 ? new ChineseChar(y).Pinyins.Select(x => x.Substring(0, first ? 1 : x.Length - 1)).First() : y.ToString()));
            
        }
}

var hanzi = "你好ma?"

var res = hanzi.ToPinYin()     //汉字转拼音
    res = hanzi.ToPinYin(true) //汉字转首字母