For example, if the server runs some flavor of Unix and has the Gnu C compiler available, you would typically use a compilation command like gcc -o mult. Instead of gcc , you might need to use cc. You really need to check local instructions for such issues. The filename extension. However, there can be server-dependent and operating system dependent rules for naming executable files.
Typical extensions for executables are. As usual when starting work with some new programming technology, you should probably first make a trivial program work. This avoids fighting with many potential problems at a time and concentrating first on the issues specific to the environment, here CGI. You could also make it the destination of a normal link in an HTML document. Note that they are not functional here. Form for submitting data Your input 80 chars max. Even though the output is declared to be plain text, Internet Explorer may interpret it partly as containing HTML markup.
Thus, if someone enters data that contains such markup, strange things would happen. The viewdata. It depends on the scripting or programming language used how a program can access the value of an environment variable. In the C language, you would use the library function getenv defined in the standard library stdlib to access the value as a string. You might then use various techniques to pick up data from the string, convert parts of it to numeric values, etc.
Effectively, it is directed so that it gets sent back to the browser. Error in passing data from form to script. Invalid data. Data must be numeric. In real life, such checks would be needed, but such considerations would take us too far from our topic. Note: The first printf function call prints out data that will be sent by the server as an HTTP header.
This is required for several reasons, including the fact that a CGI script can send any data such as an image or a plain text file to the browser, not just HTML documents.
Having compiled this program and saved the executable program under the name mult. Consequently, anyone could write a form of his own with the same ACTION attribute and pass whatever data he likes to my program. This packages the information in exactly the same way as GET methods, but instead of sending it as a text string after a?
This message comes into the CGI script in the form of the standard input. HTTP protocol is a stateless protocol. But for a commercial website it is required to maintain session information among different pages.
For example one user registration ends after completing many pages. But how to maintain user's session information across all the web pages. In many situations, using cookies is the most efficient method of remembering and tracking preferences, purchases, commissions, and other information required for better visitor experience or site statistics. Your server sends some data to the visitor's browser in the form of a cookie.
The browser may accept the cookie. If it does, it is stored as a plain text record on the visitor's hard drive. Now, when the visitor arrives at another page on your site, the cookie is available for retrieval. If this is blank, the cookie will expire when the visitor quits the browser. This may be blank if you want to retrieve the cookie from any directory or page. If this field is blank, no such restriction exists.
It is very easy to send cookies to browser. Assuming you want to set UserID and Password as cookies. So cookies setting will be done as follows. From this example, you must have understood how to set cookies. Here, it is optional to set cookies attributes like Expires, Domain, and Path.
Compile above program to produce setcookies. It is easy to retrieve all the set cookies. Now, compile above program to produce getcookies. The input tag with the file type will create a "Browse" button.
But you can try above code with your server. The solution I use is to compile my own local version of the library. Remove the shared version of the library, and link against this local version rather than the system version. It bulks up your binary, but it removes your dependency on libraries you don't control.
Once you have built your binary on the deployment system, run ldd again to make sure that all of the dynamic libraries have been found. Especially when you are linking against a local copy of a library, it's easy to forget to remove the dynamic version, which won't be found at runtime or by ldd.
Keep tweaking the build process; build and recheck until there are no unfound libraries. I make no assertions about the relative speed of C vs. The comparison that I used was the external interface to the database events. The internal interface was not tested, as calls to the external interface should dwarf calls to the internal. Apache Benchmark was used to hit each version with 10, queries, as fast as the server could take it. The C version had a mean transaction time of ms, and the PHP version had a mean transaction time of ms.
With times so close, I suspect that if the tests were repeated, some variation in time would be seen. This proved correct, although the C version was slightly faster than the PHP version more times than not. My normal development uses a more complex interface separation library, libtemplate see Resources. I have PHP and C versions of the library. When I compared versions of the event scheduler using libtemplate, I found that C had a much more favorable response time.
The mean transaction time for the C version was ms, not much more than it was for the simpler version. The PHP version had a mean transaction time of 1,ms. It also was notable that the load number while the PHP version was running generally was twice what was seen while the C version was running.
No users were on the system, and no other significant applications were running when this test was done. The fairly close times of the two C versions tell us that most of the execution time is spent loading the program.
Once the program is loaded, the program executes quite quickly. PHP, on the other hand, executes relatively slowly. Of course, PHP doesn't escape the problem of having to be loaded into memory. It also must be compiled, a step that the C program has been through already. C excels when the application requires more advanced processing and long-term stability. It is not especially susceptible to failure when server changes are beyond your control, unlike PHP.
Short of removing a shared library, such as libc or libmysqlclient, the C version of our application is hard to break. The speed of execution for C programs makes it a clear choice when the application requires more complex data processing. Clay Dowling is the president of Lazarus Internet Development www. In addition to programming, he enjoys brewing beer and wine. He can be reached by e-mail at clay lazarusid. Listing 1. Listing 2. Listing 3.
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