How to debug PHP program

How the PHP program is debug
By the way, PHP has a powerful set of code editing like VS, Project management and debugging in one IDE.
Those that are more useful and free? Thank you, everyone.

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Eclips for PHP has the error prompt function.
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Zend Studio
Installing a Zend Debugger is OK.
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PHP debugging is generally direct output, echo, Print_r. One-step test? To see the value of a variable, just echo it right now.
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Single-step debugging is in the compilation of the East, supposedly an explanatory language does not need a special debugging tools, you can change the code at any time and then look at the running effect, and do not need to compile and execute the like, breakpoints themselves arbitrarily set, want to test which block, single pull out test is, exit or die can set breakpoints
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Xampp,appserv,wamp can be. Whatever you want is next.

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