User:Brian P. Josey/Notebook/2010/09/01

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Strings and File I/O continued

Continuing on Today with my work on LabVIEW, I am slowing down the pace a little so that I can focus more on my classes and schoolwork than my research. However, I am going to attempt to work on research four hours a day on Tuesdays, Wednesdays and Thursdays.

Today, I generated a subVI that concatenates three strings into a single string. The original pair of strings contains the sentence fragment "The measurement is", while the second one is a number, and the final is the units, called a "trailer".

File I/O

File I/O stands for file input/output, and is the overall title for operations that pass data to and from files. Their several uses includes, opening and closing data files, reading data from and writing data to files, moving and renaming files and directories, and creating, modifying and reading configuration files. Of all it's functions, the palatte containing File I/O operators has four different levels: high-level, low-level, advanced and express.

Rundown of file types:

  • High Level File I/O VI's these file I/O's are used to save time and programming effort, they can be tricky as they wrap up an entire file operation into one VI.
  • Low-Level and Advanced File I/O VI's and Functions These are more simplistic, and are the bread and butter of the file i/o's. They can create or open a file, write data to or read from a file, and close a file.
  • File I/O Express VI's there are two that are used in spreadsheet style data storage.

General Process for a File I/O:

  1. Create or open a file
  2. Read from or write to the file
  3. Close the file

High-Level File I/O VI's

While most of the operators under the File I/O heading follow through only one step in the process, high-level ones wrap up the entire process into a single VI and execute it. There are not necessarily as efficient as the lower level vi's, however they simplify the programming and can be used to cut corners and make thing easier. There are several important VI's. They are:

  • Write to Spreadsheet File- converts a 1-D or 2-D array into a string and writes to a file.
  • Read from Spreadsheet File- will read a specified number of lines from a numeric text file, and converts it into a 2-D array.
  • Write Characters to File- writes a character string into a file.
  • Read Characters from File- reads a specified number of characters after an offset from a file.
  • Read Lines From File- reads a specified number of lines from a text file.
  • Binary File VI's- reads and writes to binary files.