National Instruments 320682C Using the Formatting and Scanning Functions

Chapter 2 Formatting and I/O Library

Return Code

-1 I/O error.

Parameter Discussion

If numberofBytes is -1, only the bytes in lineBuffer before the first ASCII NUL are written,

followed by a linefeed.

fileHandle is the file handle that was returned from the OpenFile function. The file should be

opened in ASCII mode so that a carriage return will be written before the linefeed. If fileHandle

is 1, the line will be written to the STDOUT.

Using This Function

WriteLine returns the number of bytes written to the file, excluding the linefeed. If an I/O

error occurs, WriteLine returns -1.

Using the Formatting and Scanning Functions

You use data formatting functions to translate or reformat data items into other forms. Typical

usages might be to translate between data stored on external files and the internal forms which

the program can manipulate, or to reformat a foreign binary representation into one on which the

program can operate.

There are three subclasses of data formatting functions in the LabWindows/CVI Formatting and

I/O Library:

• Formatting functions

• Scanning functions

• Status functions

You use formatting functions to combine and format one or more source items into a single

target item, and you use scanning functions to break apart a single source item into several target

items. The status functions return information regarding the success or failure of the formatting

or scanning functions.

To introduce you to the formatting and scanning functions, consider the following examples.