A summary of examples of common application functions in C #

This article mainly introduces C # Common application functions, combined with examples to summarize and analyze C # commonly used time, URL, HTML, reflection, fractional arithmetic and other related functions, the need for friends can refer to the following

This article summarizes the common application functions of C #. Share to everyone for your reference, as follows:

1, page write CS code (code embedded)

<%@ import namespace= "System"%><%@ import namespace= "System.Collections.Generic"%><script runat= " Server "> Public  int userId = 0;  protected void Page_Load (object sender, EventArgs e)  {    userid =convert.toint32 (request.querystring["UserId"] );    Response.Write (userId);  } </script><%  if (userId > 0) {    msg = "Welcome login!";  }  else {    msg = "User not found";  } %><%= this.msg%>

2. Get time interval

<summary>///Get time interval (time interval for simulating Weibo posts)//</summary>///<param name= "Date" ></param>///< Returns></returns>public string Getdatestr (DateTime date) {  if (date < DateTime.Now)  {    TimeSpan ts = datetime.now-date;    if (TS. TotalHours < 1 && ts. Totalminutes < 1)    {      return "1 minutes ago";    }    else if (TS. TotalHours < 1 && ts. Totalminutes > 0)    {      return Convert.ToInt32 (ts. totalminutes) + "minutes Ago";    }    else if (TS. TotalHours < 4)    {      return Convert.ToInt32 (ts. TotalHours) + "hours ago";    }    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");}

3. Iterate through the list of parameters in the URL

<summary>///traverse the list of parameters in the URL///</summary>///<returns> such as: (? userid=43&usertype=2) </returns >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;}

4. Clear the text HTML code

Using system.text.regularexpressions;///<summary>///Clear Text HTML code//</summary>public string Removehtmltag (String htmlstr) {  if (string. IsNullOrEmpty (HTMLSTR))    return string. Empty;  Return Regex.Replace (Htmlstr, @ "<[^>]*>", "");}

5. Reflection creates class instances by class name

Using system.reflection;///<summary>///reflection creates a class instance through the class name///</summary>public void Reflectest () {  Object Objclass = assembly.getexecutingassembly (). CreateInstance ("MyStudy.BLL.BookInfoBLL"); Parameter: The fully qualified name of the class, without the suffix name of the class  if (objclass! = null)  {    Bookinfobll BLL = (BOOKINFOBLL) objclass;  }}

6. Currency type conversion

<summary>///currency///</summary>///<param name= "obj" ></param>///<returns></ Returns>public static string Tomoney (Object obj) {  return String.Format ("{0:c}", obj);}

7. Number of decimal places

1. Number of decimal places String str1 = String.Format ("{0:f1}", 56789); Result:56789.0string str2 = String.Format ("{0:f2}", 56789); Result:56789.00string STR3 = String.Format ("{0:n1}", 56789); Result:56,789.0string STR4 = String.Format ("{0:n2}", 56789); Result:56,789.00string STR5 = String.Format ("{0:n3}", 56789); Result:56,789.000string STR6 = (56789/100.0). ToString ("#.##"); Result:567.89string STR7 = (56789/100). ToString ("#.##"); Result:567//2. Reserved n bits, rounded. Decimal d= decimal. Round (decimal. Parse ("0.55555"), 2);//3. Reserve N-bit rounding Math.Round (0.55555, 2);

8, using TryGetValue to improve access to the dictionary worth the performance

Use TryGetValue to increase the performance of a large number of values by a factor of containskey.

dictionary<int, string> dic = new Dictionary<int, string> ();d IC. ADD (1, "Zhang San");d IC. ADD (2, "John Doe"); string name = "";//error notation, efficiency bottom if (dic.  ContainsKey (1)) {name = Dic[1]; Console.WriteLine (name);} Correct wording, increase efficiency by one-times if (DIC. TryGetValue (1, out name)) {Console.WriteLine (name);}