How to use image magick with php

Use PHP

This section covers many errors that you may encounter while writing PHP scripts.

  1. I can't remember the order of the parameters of PHP functions - is there a scheme?
  2. I want to write a PHP script that can process data from any form. How do I know which variables are available through the POST method?
  3. I want to have all single quotation marks (') replaced with a backslash followed by a single quotation mark (\'). How can I do this with a regular expression? I also want to convert "to \" and \ to \.
  4. When I run the following code, the output is out of order: Why is that?
  5. Where have my line breaks gone?
       
  6. I get the message 'Warning: Cannot send session cookie - headers already sent ...' or 'Cannot add header information - headers already sent ...'.
  7. How can I access information from the request header?
  8. When I try to use authentication with IIS, I get the message 'No Input file specified'.
  9. Windows: I cannot access files shared on another computer when using IIS.
  10. How can I mix XML and PHP? PHP is complaining about my
  11. Where can I find a complete list of the variables available to me?
  12. How can I generate PDF files without using the non-free and commercial PDFLib library? I'm looking for something that is free and doesn't require any external PDF libraries.
  13. Some PHP directives accept not only integer byte values, but also abbreviated byte values. What are the abbreviations?
I can't remember the order of the parameters of PHP functions - is there a scheme?

PHP is made up of hundreds of external libraries, so this can seem a bit confused at times. But a simple rule is as follows:

Array function parameters are defined as "needle, haystack"(Needle, haystack) ordered, while the parameters of string functions are ordered exactly the other way around, so as"haystack, needle"(Haystack, needle).

I want to write a PHP script that can process data from any form. How do I know which variables are available through the POST method?

PHP offers many predefined variables, like the superglobal. You can iterate with a loop because it is an associative array with all the variables transferred via the POST method. As an example, we use the foreach loop to check for empty values ​​(with the empty () function) and output these values.

I want to have all single quotation marks (') replaced with a backslash followed by a single quotation mark (\'). How can I do this with a regular expression? I also want to convert "to \" and \ to \.

If you want to do this for a database, you should use the masking mechanism provided for that database. E.g. you should use mysql_real_escape_string () under MySQL and pg_escape_string () under PostgreSQL. There are also the generic functions addslashes () and stripslashes (), which are often used in older PHP code.

When I run the following code, the output is out of order: Why is this?

In order to be able to use the result of your function in an expression (e.g. to connect it to the other string as in the example above), you have to return the value with return and not output it with echo.

Where have my line breaks gone?

In PHP, blocks of code can end with either "?>" Or "?> \ N" (\ n stands for line break). In the example above, the output lines are therefore in one line, because PHP omits the line breaks after the end-of-block characters. If you want PHP to return a line break, you'll need to add an extra line break after each block of code.

Why does PHP do this? If you format normal HTML, PHP makes your work easier because you usually don't want this line break at all. If PHP printed this line break, you'd have to write very long lines, making your code unreadable.

I get the message 'Warning: Cannot send session cookie - headers already sent ...' or 'Cannot add header information - headers already sent ...'.

The functions header (), setcookie () and the session functions must add headers to the output stream. However, headers can only be sent if they are sent before any other data. No output (such as HTML code) may take place before these functions are called. The headers_sent () function checks whether your script has already sent headers. The output control functions are also useful in this context.

How can I access information from the request header?

If you run PHP as an Apache module, the getallheaders () function provides you with the information you need. The following code prints all request headers:

See also apache_lookup_uri (), apache_response_headers () and fsockopen ().

When I try to use authentication with IIS, I get the message 'No Input file specified'.

The IIS security model is flawed here. This is a problem that occurs with all CGI programs that run under IIS. As a workaround, you can put an empty HTML file that is not parsed by PHP as an entry page in a directory protected by authentication. You then redirect the browser to the PHP page using a META tag or you set a link to the PHP page. PHP then correctly recognizes the authentication. This problem should not occur on other NT web servers either. You can find more information here: »http://support.microsoft.com/kb/q160422/. Also read the manual section on HTTP authentication with PHP.

Windows: I cannot access files shared on another computer when using IIS.

You have to change that. Find your PHP file and view its properties. Switch to the register and click on there.

You can fix the problem by either unchecking the box and leaving it at, or by ticking and then adjusting the permissions of the users who should not have access.

How can I mix XML and PHP? PHP is complaining about my

To insert

Where can I find a complete list of the variables available to me?

Read the predefined variables manual page for an (incomplete) list of the predefined variables available to your scripts. A complete list of the available variables (and much more information) can be seen by calling the phpinfo () function. Also note the section on variables outside of PHP, which describes different scenarios for external variables such as HTML forms, cookies or the URL.

How can I generate PDF files without using the non-free and commercial PDFLib library? I'm looking for something that is free and doesn't require any external PDF libraries.

There are a few alternatives written in PHP such as »FPDF and» TCPDF.

Some PHP directives accept not only integer byte values, but also abbreviated byte values. What are the abbreviations?

The available abbreviations are K (for kilobytes), M (for megabytes) and G (for gigabytes), case-insensitive. All other values ​​are recognized as byte values. corresponds e.g. B. a megabyte or bytes. corresponds to a kilobyte or bytes. This abbreviated notation can be used in and in the ini_get () function. Note that the numeric value is converted to int; for example is interpreted as.

Note: Kilobytes versus Kibibytes

The PHP notation describes a kilobyte as the equivalent of 1024 bytes, while the standard describes this as a kibibyte. Summary: k and K = 1024 bytes.

robjbrain at gmail dot com