Use PHP's ob_start; to control your browser cache!

<span><br> <span><?php <BR>ob_start</SPAN><SPAN>(); </SPAN><SPAN>//Open buffer <BR></SPAN><SPAN>echo </SPAN><SPAN>"Hellon"; //Output <BR>header("</SPAN><SPAN>location</SPAN> <SPAN>:</SPAN><SPAN>index</SPAN> <SPAN>.</SPAN><SPAN>php</SPAN><SPAN>"); //Redirect the browser to index.php <BR>ob_end_flush();//Output all the content to the browser <BR>?> <br> </span></span>
Anyone who knows the header() function knows that this function will send a file header to the browser, but if there is any output before using this function (including empty output, such as spaces, carriage returns and line feeds) An error will be prompted. If we remove ob_start() in the first line and then execute this program, we will find that we get an error message: "Header had all ready send by"! But with ob_start, there will be no error message. The reason is that when the buffer is opened, the characters after echo will not be output to the browser, but will be retained on the server. They will not be output until you use flush or ob_end_flush, so it will not Any file header output errors!
1. Introduction to related functions:
1. Flush: refresh the contents of the buffer and output.
Function format: flush()
Description: This function is frequently used and is very efficient.
2. ob_start: Open the output buffer
Function format: void ob_start(void)
Description: When the buffer is activated, all non-file header information from the PHP program will not be sent, but will be saved in the internal buffer. In order to output the contents of the buffer, you can use ob_end_flush() or flush() to output the contents of the buffer.
3, ob_get_contents: Return the contents of the internal buffer.
Usage: string ob_get_contents(void)
Description: This function will return the contents of the current buffer. If the output buffer is not activated, it will return FALSE.
4. ob_get_length: Returns the length of the internal buffer.
Usage: int ob_get_length(void)
Description: This function will return the length in the current buffer; like ob_get_contents, if the output buffer is not activated. then returns FALSE.
5. ob_end_flush: Send the contents of the internal buffer to the browser and close the output buffer.
Usage: void ob_end_flush(void)
Description: This function sends the contents of the output buffer (if any).
6. ob_end_clean: Delete the contents of the internal buffer and close the internal buffer.
Usage: void ob_end_clean(void)
Explanation: This function will not output the contents of the internal buffer but delete it!
7. ob_implicit_flush: Turn on or off absolute flush
Usage method: void ob_implicit_flush ([int flag])
Note: Anyone who has used Perl knows the meaning of $|=x. This string can open/close the buffer, and The ob_implicit_flush function is the same as that one. The default is to close the buffer. After turning on absolute output, each script output is sent directly to the browser, and there is no need to call flush().
Second, in-depth understanding:
1. About the Flush function:
This function has appeared in PHP3 and is a very efficient function. It has a very useful function of refreshing the browser's cache. Let's give an example with a very obvious operating effect to illustrate flush.
Example 2.