Recent Notes

Displaying keyword search results 1 - 4
Created by jinx on April 25, 2011 12:43:40    Last update: April 25, 2011 12:43:40
Use the PHP function method_exists to check if the class or object has a certain method. It returns TRUE if the method exists (even when the value of the property is NULL), FALSE if the method does not exist. Example: <?php class A { var $p = 'A property'; ... Outputs: Class A has method f1: bool(true) Object $a has... Also note that C++-like method overloading does not exist in PHP. Thus there's no ambiguity about which version of the method exists, i.e., with no argument, with one argument... etc. The following code generates Fatal error: <?php class A { var $p = 'A property'; ...
Created by jinx on April 25, 2011 11:50:09    Last update: April 25, 2011 11:51:53
Use the PHP function property_exists to check if the class or object has a certain property. It returns TRUE if the property exists (even when the value of the property is NULL), FALSE if the property does not exist, or NULL in case of an error. Example: <?php class A { var $p = 'A property'; ... Outputs: Class A has property $p: bool(false) Class A ha...
Created by Dr. Xi on December 04, 2009 04:33:05    Last update: December 04, 2009 04:33:05
Variable Meaning $_ The default or implicit variable. @_ Within a subroutine the array @_ contains the parameters passed to that subroutine. $a, $b Special package variables when using sort() $<digit> Contains the subpattern from the corresponding set of capturing parentheses from the last pattern match, not counting patterns matched in nested blocks that have been exited already. $. Current line number for the last filehandle accessed. $/ The input record separator, newline by default. $| If set to nonzero, forces a flush right away and after every write or print on the currently selected output channel. Default is 0 (regardless of whether the channel is really buffered by the system or not; $| tells you only whether you've asked Perl explicitly to flush after...
Created by Dr. Xi on May 29, 2007 03:48:01    Last update: May 29, 2007 03:49:54
The following applies to Bourne, Korn and Bash: $var or ${var} Replaced by the value of var . Use braces to avoid ambiguity. ${var-value} Use the value of var if set, use value otherwise. ${var+value} Use the value of value if var is set, use nothing otherwise. ${var=value} Use the value of var if set, other wise, use value and assign value to var . ${var?value} Use the value of var ; otherwise, print value to standard error and exit the current shell. If value is omitted, a standard error message is printed instead.