运行我的应用程序时出现的错误 [英] error that i gt when i run my application

问题描述

对象引用未设置为对象的实例.在第68行:while(dr.Read())我不明白该错误，请帮助pple !!!

Object reference not set to an instance of an object. in Line 68: while (dr.Read()) i do not understand that error please help pple!!!

推荐答案

如果您确定引发了异常恰好在该行中，这仅意味着dr等于null.检查此对象的构造位置，并确保在取消引用时该对象不为null；或更改代码的逻辑以检查if (dr != null) …以仅在不为null时使用它.始终在调试器下运行它，以确保所有对象都获得适当的值.

实际上，只要您对运行时行为有一点担忧，就应该使用调试器(不仅当您遇到意外的异常时)，而且在提出问题之前也应使用调试器.做功课，以充分利用可能获得的帮助.

—SA

If you are sure that the exception is thrown exactly in that line, it can only mean that dr is equal to null. Check up where this object is constructed and make sure it''s not null at the moment of de-referencing; or change the logic of the code to check if (dr != null) … to use it only when it is not null. Always run it under debugger to make sure all object gets appropriate value.

Actually, you should use the debugger whenever you have a slightest concern about your run-time behavior (not only when you have an unexpected exception), and also before you ask a question. Do your homework to get the most from the help you may get.

—SA

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