C # common character Functions

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. system. Text. encoding. Default. getbytes (variable)
Convert character code to bit code
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. String user_ip = request. servervariables ["remote_addr"]. tostring ();
Obtain the IP address of a remote user

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. session ["variable"];
Access session value;
For example, assign a value: session ["username"] = "";

Value: Object objname = session ["username"];
String strname = objname. tostring ();
Clear: Session. removeall ();

11. String STR = request. querystring ["variable"];
Use hyperlinks to send variables.
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. Doc object. createelement ("new node name ");
Create a new node for the XML document

13. parent node. appendchild (child node );
Add the new child node to the XML document parent node.

14. parent node. removechild (node );
Delete a node

15. Response
Response. Write ("string ");
Response. Write (variable );
Output to the page.

Response. Redirect ("url address ");
Jump to the page specified by the URL

16. Char. iswhitespce (STRING variable, digits) -- Logical type
Check whether the specified position contains null characters;
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. Char. ispunctuation ('characters') -- Logical type
Check whether a character is a punctuation mark.
For example: Response. Write (char. ispunctuation ('A'); // return: false

18. (INT) 'characters'
Convert the character into a number and check the code. Note that it is a single quotation mark.
For example:
Response. Write (INT) 'in'); // The code with the result of a Chinese character: 20013

19. (char) Code
Convert the number into characters and check the characters represented by the Code.
For example:
Response. Write (char) 22269); // return the word "country.

20. Trim ()
Clear leading and trailing Spaces

21. string variable. Replace ("substring", "Replace ")
String replacement
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 ("& lt;", "<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. Math. Max (I, j)
Take the maximum value in I and j.
For example, int x = math. Max (5, 10); // X, the value is 10.

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

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

(1 ),
String str1; str2
// Syntax: str1.endswith (str2); _ check whether str1 ends with str2 and returns a Boolean value. For example:
If (str1.endswith (str2) {response. Write ("string str1 ends with" + str2 + ");}

(2 ),
// Syntax: str1.equals (str2); _ check whether str1 is equal to str2. Return a Boolean value, which is the same as the preceding syntax.

(3 ),
// Syntax equals (str1, str2); _ checks whether str1 is equal to str2 and returns a Boolean value.

24. indexof (), lastindexof ()
Search for the position where the specified character or string appears for the first time (the last time) in the string, and return the index value, for example:
Str1.indexof ("word"); // search for the index value (location) of the word in str1)
Str1.indexof ("string"); // search for the index value (location) of the first character of "string" in str1)
Str1.indexof ("string", 4th); // query the index value (location) of the first character of the "string" in str1 for 2 characters starting from str1 characters)

25. insert ()
Insert the specified character into the specified index position in the string. For example:
Str1.insert (1, "word"); Insert "word" to the second character of str1. If str1 = "China", it is inserted as "Chinese country ";

26. padleft (), padright ()
Add a space or a specified char character to the left (or right) of the string so that the string reaches the specified length, for example:
<%
String str1 = "Chinese ";
Str1 = str1.padleft (10, '1'); // No second parameter is added with Space
Response. Write (str1); // The result is "1111111 Chinese" and the string length is 10.
%>

27. Remove ()
Deletes a specified number of characters from a specified position.
String comparison is generally used: If (str1 = str2) {}, but there are other methods: