C#常见应用函数实例小结

 <%@ Import Namespace="System" %><%@ Import Namespace="System.Collections.Generic" %> <% if (userId > 0){ msg = "欢迎登录!"; } else { msg = "未找到用户"; } %> <%= this.msg %> 

 /// 
 /// 获取时间间隔（模拟微博发布文章的时间间隔） /// 
 ///  ///  public string GetDateStr(DateTime date) { if (date < DateTime.Now) { TimeSpan ts = DateTime.Now - date; if (ts.TotalHours < 1 && ts.TotalMinutes < 1) { return "1分钟前"; } else if (ts.TotalHours < 1 && ts.TotalMinutes > 0) { return Convert.ToInt32(ts.TotalMinutes) + "分钟前"; } else if (ts.TotalHours < 4) { return Convert.ToInt32(ts.TotalHours) + "小时前"; } else if (DateTime.Now.Date == date.Date) { return date.ToString("HH:mm"); } else { return date.ToString("yyyy-MM-dd"); } } return date.ToString("yyyy-MM-dd"); } 

 /// 
 /// 遍历Url中的参数列表 /// 
 /// 如:(?userId=43&userType=2) public string GetUrlParam() { string urlParam = ""; if (Request.QueryString.Count > 0) { urlParam = "?"; NameValueCollection keyVals = Request.QueryString; foreach (string key in keyVals.Keys) { urlParam += key + "=" + keyVals[key] + "&"; } urlParam = urlParam.Substring(0, urlParam.LastIndexOf('&')); } return urlParam; } 

 using System.Text.RegularExpressions; /// 
 /// 清除文本HTML码 /// 
 public string RemoveHtmlTag(string htmlStr) { if (string.IsNullOrEmpty(htmlStr)) return string.Empty; return Regex.Replace(htmlStr, @"<[^>]*>", ""); } 

 using System.Reflection; /// 
 /// 反射 通过类名创建类实例 /// 
 public void ReflecTest() { Object objClass = Assembly.GetExecutingAssembly().CreateInstance("MyStudy.BLL.BookInfoBLL"); //参数：类的完全限定名，无需类的后缀名 if (objClass != null) { BookInfoBLL bll = (BookInfoBLL)objClass; } } 

 /// 
 /// 货币 /// 
 ///  ///  public static string ToMoney(object obj) { return String.Format("{0:C}", obj); } 

 //1.小数点位数 string str1 = String.Format("{0:F1}", 56789); //result: 56789.0 string str2 = String.Format("{0:F2}", 56789); //result: 56789.00 string str3 = String.Format("{0:N1}", 56789); //result: 56,789.0 string str4 = String.Format("{0:N2}", 56789); //result: 56,789.00 string str5 = String.Format("{0:N3}", 56789); //result: 56,789.000 string str6 = (56789 / 100.0).ToString("#.##"); //result: 567.89 string str7 = (56789 / 100).ToString("#.##"); //result: 567 //2.保留N位,四舍五入 . decimal d= decimal.Round(decimal.Parse("0.55555"),2); //3.保留N位四舍五入 Math.Round(0.55555, 2); 

 Dictionary dic = new Dictionary(); dic.Add(1,"张三"); dic.Add(2,"李四"); string name = ""; //错误写法，效率底 if (dic.ContainsKey(1)) { name = dic[1]; Console.WriteLine(name); } //正确写法，效率提高一倍 if (dic.TryGetValue(1, out name)) { Console.WriteLine(name); }