Visual C # Summary of common functions and methods

1. DateTime numeric type

System. DateTime currentTime = new System. DateTime ();
1.1 take the current year, month, day, hour, minute, second

CurrentTime = System. DateTime. Now;
1.2 get current year

Int Year = currentTime. Year;
1.3 take the current month

Int Month = currentTime. Month;
1.4 get the current day

Int Day = currentTime. Day;
1.5 current time

Int = currentTime. Hour;
1.6 get the current score

Int = currentTime. Minute;
1.7 takes the current second

Int Second = currentTime. Second;
1.8 takes the current millisecond

Int Millisecond = currentTime. Millisecond;
(The variable can be in Chinese)
1.9 display Chinese date -- year, month, and day

String strY = currentTime. ToString ("f"); // seconds not displayed
1.10 use Chinese date to display _ year and month

String strYM = currentTime. ToString ("y ");
1.11 retrieve Chinese Date display _ month/day

String strMD = currentTime. ToString ("m ");
1.12 take the current year, month, and day in the format of 2003-9-23

String strYMD = currentTime. ToString ("d ");
1.13 get the current time, format: 14: 24

String strT = currentTime. ToString ("t ");
2. Convert string type to 32-digit font

Int32.Parse (variable) Int32.Parse ("constant ")

3. Variable. ToString ()

Convert string to string
12345. ToString ("n"); // generate 12,345.00
12345. ToString ("C"); // generate $12,345.00
12345. ToString ("e"); // generate 1.234500e + 004
12345. ToString ("f4"); // generate 12345.0000
12345. ToString ("x"); // generate 3039 (hexadecimal)
12345. ToString ("p"); // generate 1,234,500.00%

4. Variable. Length numeric type

String Length:

For example, string str = "China ";

Int Len = str. Length; // Len is a custom variable, and str is the variable name of the string to be tested.
5. Convert the character code into a bit code

System. Text. Encoding. Default. GetBytes (variable)

For example, byte [] bytStr = System. Text. Encoding. Default. GetBytes (str );

Then we can get the bit length:

Len = bytStr. Length;

6. System. Text. StringBuilder ("")

String addition, (is the same as the + number ?)

For example:

System. Text. StringBuilder sb = new System. Text. StringBuilder ("");
Sb. Append ("China ");
Sb. Append ("people ");
Sb. Append ("Republic ");
7. Variable. Substring (parameter 1, parameter 2 );

Part of the string to be truncated. Parameter 1 is the start number of digits on the left, and parameter 2 is the number of digits to be truncated.

For example, string s1 = str. Substring );

8. Obtain the IP address of a remote user.

String user_IP = Request. ServerVariables ["REMOTE_ADDR"]. ToString ();
9. Obtain the real IP address of the remote user through the proxy server:

If (Request. ServerVariables ["HTTP_VIA"]! = Null ){
String user_IP = Request. ServerVariables ["HTTP_X_FORWARDED_FOR"]. ToString ();
} Else {
String user_IP = Request. ServerVariables ["REMOTE_ADDR"]. ToString ();
}
10. Access Session Value

Session ["variable"];
For example, assign a value:

Session ["username"] = "Bush ";
Valid value:

Object objName = Session ["username"];
String strName = objName. ToString ();
Clear:

Session. RemoveAll ();
11. Send variables with hyperlinks

String str = Request. QueryString ["variable"];
For example, create a hyperlink on any page: <a href = Edit. aspx? Fbid = 23> click </a>

On the Edit. aspx page, set the value to String str = Request. QueryString ["fdid"];

12. Create a new node for the XML document

DOC object. CreateElement ("new node name ");

13. Add the new child node to the parent node of the XML document.

Parent node. AppendChild (child node );

14. delete a node

Parent node. RemoveChild (node );

15. output to the page: Response

Response. Write ("string ");
Response. Write (variable );
Jump to the page specified by the URL:

Response. Redirect ("URL address ");
16. Check whether the specified position contains null characters.

Char. IsWhiteSpce (STRING variable, number of digits) -- Logical type;
For example:

String str = "Chinese people ";
Response. Write (char. IsWhiteSpace (str, 2); // The result is True. The first character is 0, and the second is the third character.
17. Check whether the character is a punctuation mark.

Char. IsPunctuation (character) -- Logical type
For example:

Response. Write (char. IsPunctuation (A); // return: False
18. Convert the character into a number and check the code. Note that it is a single quotation mark.

(Int) character

For example:

Response. Write (int); // The code with the result of a Chinese character: 20013
19. Convert the number into characters and check the characters represented by the Code: (char) Code

For example:

Response. Write (char) 22269); // return the word "country.
20. Clear spaces before and after the string: Trim ()

21. String replacement

String variable. Replace ("substring", "Replace ")

For example:

String str = "China ";
Str = str. Replace ("country", "Central"); // Replace the Chinese character with the central character
Response. Write (str); // The output result is "Central"
Another example is: (this is very practical)

String str = "This Is A <script> script ";
Str = str. replace ("<", "<font> </font> "); // Replace the left angle brackets with <font> and </font> (or replace them with <, but it is estimated that after saving the XML, it will be restored again)
Response. Write (str); // display as: "This is a <script> script"
If not replaced, <script> is not displayed. If it is a script, it runs. If it is replaced, the script does not run.

The value of this Code is that you can invalidate and display all HTML tags in a text file to protect your interactive websites.

Specific implementation: Add the following code to your form submission button script:

String strSubmit = label1.Text; // label1 is the Control ID for you to submit data.
StrSubmit = strSubmit. Replace ("<", "<font> </font> ");
Then save or output strSubmit.

This method can also be used to easily implement the UBB code.

22. Maximum values in I and j: Math. Max (I, j)

For example, int x = Math. Max (5, 10); // x, the value is 10.

Add a bit. 23. String comparison ......

23. String comparison is generally used: if (str1 = str2) {}, but there are other methods:

(1 ),

String str1; str2
// Syntax: str1.EndsWith (str2); _ Check string str1 is