How To Write/Read to/from an External File

 

Overview

This sample demonstrates how to write data to and read data from an external file on the device.

The attached survey implements the following functionality:

• When the respondent answers Yes to Q1, the WriteFileText() function writes two lines of text to a file. The sample uses the second overload of the function, which also attaches the file to the interview.

• Because the file may not be closed immediately after the write operation completes, an Empty question (Q2) is included before attempting to read the file. This ensures the file has been closed before it is accessed.

  Note: You can use the OnWriteFileTextResult(inFileName, inSuccess, inAppended) callback function to determine when the write operation has finished.

• An Expression question (Q3) then calls the ReadFileText() function in its Answers tab to read the contents of the file.

The attached survey can be downloaded using the link at the bottom of this article.

1. Q4 is the same as Q2 an extra question that will let the function finish reading from the file.
2. Q5 an Open Ended question that will show the text that was written to the file.