Writing Web Pages By Shyam Gurram Agenda Writing
Writing Web Pages By Shyam Gurram
Agenda • • Writing Web Pages Delimiting PHP Program Units. Displaying Output to Web Pages Putting Comments in PHP Programs
Writing Web Pages • As we said discussed in the previous chapter, PHP is a server-side scripting or programming language. The primary purpose of server-side programming language is to generate HTML web pages. This language can be used to generate a complete a web page but is generally used as part of static or dynamic web page. • We need to learn the following concepts to create a Web pages in an effective manner. Delimiting PHP program units. Displaying output to web pages. Putting comments in PHP programs.
Delimiting PHP Program Units. • We have four possible styles to use for embedding PHP in your web pages. Default style ( Using the tags <? php and ? >) HTML style script delimiters (<script language = “PHP”> and </script>) Short tags (<? and ? >) ASP-style tags (<% and %>) • Among the four short tags and ASP-style tags save very little and present more issues than benefits.
• <html> <head> <title> Default Style • The default syntax for embedding PHP programming units in your web page is the <? php and ? >. • PHP Program consists of single statement followed by a semicolon. PHP info test page </title> </head> <body> <? php. Info(); ? > </body> </html>
• <html> <head> Delimiting PHP Program Units Conti. . • PHP also supports a script delimiter. • The Scripting syntax for embedding PHP programming units in our web pages consists of the<script language=“php”> and </script>. <title> PHP info test page </title> </head> <body> <script language=php > php. Info(); </script> </body> </html>
• <html> <head> Delimiting PHP Program Units Conti. . • PHP supports short tags provided you enable them in the php. ini configuration file. • Short tags will have a little advantage and can lead to confusion, if you want to use them, the scripting syntax uses <? And ? >. <title> PHP info Short-tag test page </title> </head> <body> <? php. Info(); ? > </body> </html>
• <html> <head> Delimiting PHP Program Units Conti. . • PHP supports Micro ASP page syntax, in order to use the ASP page you need to enable in the php. ini configurations script by editing the asp_tags directive. <title> PHP info Short-tag test page </title> </head> <body> • If you want to use them scripting <% php. Info(); %> • If you chose to enable asp_tags in </body> syntax uses <% and % >. your php. ini file, you will need to restart your HTTPD for those changes to take effect. </html>
Displaying Output to Web Pages • There are two predefined PHP constructs and functions are used to display output to web pages. • The difference between a function and a construct is that the parentheses are unnecessary in a construct. • The first constructor is the echo() statement. General syntax for the echo statement is void echo(string arg 1 [, string arg 2…]) • The limitation of the echo() constructor is that it returns nothing and therefore cannot be used in complex expression.
• <html> <head> Displaying Output to Web Pages • Each line that uses the echo() construct must be terminated by semicolon, which makes the lines statement of execution. • In the echo() statement, if you want to pass multiple arguments to the ecjo command parentheses cannot be used. <title> PHP echo() construct test page </title> </head> <body> <? echo(“Hello one ! ”); echo “Hello Two! ” ; ? > </body> </html>
Displaying Output to Web Pages • There are several escape sequences that may likewise be included in the argument or argument list to the echo() construct. • • • is the web browser to perform a line break. The /t is the escape sequence for a tab. The /n is the escape for a new line. The r is the escape sequence for a carriage return. The $ symbol is used to designate variables. The backslash is used to back-quote, and double quotes are used to delimit string values.
Displaying Output to Web Pages • The second constructor is the print() statement. • The benefit of the print() constructor is that it always returns an int value 1. This means that it used in complex expression. • The difference between the print() and echo() construct is that the print() construct does not support multiple arguments with or without parenthesis. int print(string arg)
Displaying Output to Web Pages • There are two predefined PHP functions, they are printf() and vprintf(). • The printf() function outputs a formatted string. printf(format, arg 1, arg 2, arg++) • Required. Specifies the string and how to format the variables in it. Possible • • format values: %% - Returns a percent sign %b - Binary number %c - The character according to the ASCII value %d - Signed decimal number (negative, zero or positive)
Displaying Output to Web Pages • • • %e - Scientific notation using a lowercase (e. g. 1. 2 e+2) %E - Scientific notation using a uppercase (e. g. 1. 2 E+2) %u - Unsigned decimal number (equal to or greather than zero) %f - Floating-point number (local settings aware) %F - Floating-point number (not local settings aware) %g - shorter of %e and %f
Displaying Output to Web Pages • %G - shorter of %E and %f • %o - Octal number • %s - String • %x - Hexadecimal number (lowercase letters) • <? php $number = 123; printf("%f", $number); ? >
Displaying Output to Web Pages • The next function is vprintf() which is similar to printf(). • vprintf() returns a formatted string, Operates as printf() but accepts an array of arguments, rather than a variable number of arguments.
Putting Comments in PHP Programs • The PHP programming language supports two styles of writing comments. • Single-Lime Comment: These are used to comment the single line of code by using the forward slashes. • // , # This is a single line comment • Multiple-Line Comment: This is used to comment multiple lines of code. • /* This is a multiple-line comment. */
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