eval是什么，相信很多都会知道。但真实有多少人使用它呢？恐怕在实际应用中，使用的也比较少吧。(详细请看全文)
Evaluates the string given in code_str as PHP code. Among other things, this can be useful for storing code in a database text field for later execution.
There are some factors to keep in mind when using eval(). Remember that the string passed must be valid PHP code, including things like terminating statements with a semicolon so the parser doesn't die on the line after the eval(), and properly escaping things in code_str. To mix HTML output and PHP code you can use a closing PHP tag to leave PHP mode.
Also remember that variables given values under eval() will retain these values in the main script afterwards.
» 阅读全文