Fix the error of getNextFileName function
Fix the error of the name of filesystem and clear the buffer to zero
Fix the error of the getNextFileName function
1.At the end of the function, the buffer doesn't be clean.
2.Let the charater correctly be  stored in the buffer.
Fix the error of the getNextFileName function
1.Fix the return value.
2.Use the '\t' to represent the end of the name of file.