Simple use of the input (File) control!

The input (File) control is mainly used to upload files to the server. The following example shows how to use the input (File) control:

Open. NET and drag an input (File) control on the page, right-click it, select "run as a server control", and drag a button and an image

Add the following to the button event:Code:

Protected void button#click (Object sender, eventargs E)
{
String fullname = This. file1.postedfile. filename; // obtain the complete path and file name of the file on the client.
String name = fullname. substring (fullname. lastindexof ("\") + 1); // The string truncation function retrieves the file name.
String type = Name. substring (name. lastindexof (".") + 1); // The string truncation function gets the file suffix
If (type = "jpg" | type = "BMP" | type = "GIF") // you can determine whether the image is an image.
{
This. file1.postedfile. saveas (server. mappath ("up") + "\" + name); // upload to the server up directory
This. image1.imageurl = "up/" + name; // Image Display
}
Else
{
Response. Write ("<script language = 'javascript '> alert ('the format of the image you selected is incorrect! ') </SCRIPT> ");
}
}
The test passed on. net2005. If it is in another format, you can change the corresponding suffix. To prevent duplicate names, you can use a random function to rename the name variable together with the date!

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Appendix: indexof () substring () function usage:

Indexof (): locates the character and string from the front to the back in the string. All return values are absolute positions in the string. If it is null, it is-1.

String test = "asdfjsdfjgkfasdsfsgfhgjgfjgdddd ";

Test. indexof ('D') = 2 // locate the location where D appears for the first time.
Test. indexof ('D', 1) = 2 // locate the first position where D appears from the third string
Test. indexof ('D', 5, 2) = 6 // locate D from the front to the back and query it from 5th bits. Check for 2 bits, that is, from 5th bits to 7th bits;

Lastindexof (): locates the character and string from the back and forward in the string ;,
The usage is exactly the same as that of indexof.

The following describes indexofany | lastindexofany.

They accept the character array as the variable element. The other methods are the same as above, and return the subscript location of any character in the array.

As follows:

Char [] bbv = {'s ', 'C',' B '};
String abc = "acsdfgdfgchacstcsad ";

Response. Write (ABC. indexofany (bbv) = 1
Response. Write (ABC. indexofany (bbv, 5) = 9
Response. Write (ABC. indexofany (bbv, 5, 3) = 9

Lastindexofany is the same as above.
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Substring () Usage

String A = "aadsfdjkfgklfdglfd"

A. substring (5) // capture all strings after the fifth digit

A. substring (0th) // intercept all strings from 5th

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