PHP

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Reference

• PHP Homepage
• Hardened PHP: patches to improve PHP security

Newbie Traps & Pitfalls

PHP will let you get away with a lot of syntax mistakes which are perfectly valid code (often creating unexpected variables in the process) but not what you intended. Most of the following produced no immediate error messages; the code simply wouldn't work, and it took me several edit-upload-run cycles to find each problem. Here are some mistakes I made when re-learning PHP in 2005 after not using it since 1997:

• Classes
  • Member vars and functions must always be referred to using $this->FunctionName()
  • However, var members do not take a $ prefix: $this->varName
  • If you pass an object to a function, the function will be operating on a copy of the object unless the function is called with the object passed as a reference: CalledFunction(&$objName);. The function declaration itself needs no modifications.
  • If the function is expected to store the object for later use (e.g. it is a class constructor), the function must also use a reference when saving the object: $this->localName =& $iObjectParam;. Otherwise (again) it will be using a copy, not the original.
• Operators
  • The "is equal to" comparison operator is "==" (as in c/c++), not "="