How to open the file in class in mfc?

While trying to open the file in Class in function oninitdialo开发者_JAVA技巧g(),It throws exception.If I open the file globally , it works. How to overcome this? why the fopen command is behaving like these?

Regards,

karthik

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Actually I made a mistake by creating file descriptor in OninitDialog function in mfc.To overcome this , I create the file descriptor in constructor of the class.