Difference between revisions of "PHP"
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PHP will let you get away with a lot of syntax mistakes which are perfectly valid code 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: | PHP will let you get away with a lot of syntax mistakes which are perfectly valid code 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 | *Classes | ||
**Member vars and functions must ''always'' be referred to using '''$this-> | **Member vars and functions must ''always'' be referred to using '''$this->''FunctionName''()''' | ||
**However, var members do not take a $ prefix: '''$this->varName''' | **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 | *Operators | ||
**The "is equal to" comparison operator is "==" (as in c/c++), not "=" | **The "is equal to" comparison operator is "==" (as in c/c++), not "=" | ||
Revision as of 17:25, 24 July 2005
Reference
Newbie Traps & Pitfalls
PHP will let you get away with a lot of syntax mistakes which are perfectly valid code 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 "="