About the PHP excution, it's line-by-line or file-by-file?

PHP is execute line by line or just like java that it's compiled form byte开发者_运维百科 code to binary code file by file?

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The whole files is parsed before anything get executed. After this parser, PHP runs instruction by instruction. If your first instruction is a require/include, PHP will open the file and read their instructions (layered)

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PHP translates sources into opcode and after that evaluates it instruction by instruction.

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It's executed instruction by instruction. But before it gets executed, the whole file is parsed. Thus a syntax error occurs before anything gets executed.

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You can see PHP is not executed line-by-line, because you get syntax errors from whole file even before first line was executed (even in function which are not called at all).

If you want an example of line-by-line language, see Windows command line (it applies to unix sh files too) batch file language - you can type anything into lines which are not executed (for example because you terminate the file before the line gets parsed) and you won't get any kind of error.