File Input and Output

1
File Input and Output

• Sequential Access Files

2
Format Function

• Syntax
• Format(expression, format)
• Example
• lblNumber.Caption You owe Format(dblSum,
  "Currency")
• or
• picOutput.Print Format(dblAnswer, Fixed)

3
Built-in Numeric Formats

• General Number
• Currency
• Fixed
• Standard
• Percent
• Scientific

4
User-defined Number Formats

• 0 display digit or zero
• display digit or nothing
• . decimal placeholder
• , thousands separator
• percent
• - display the literal character
• lblTaxes.Caption Format(dblDollars,,0.00")

5
Sequential Access Files

• each record appears on a separate line
• fields are separated by commas
• "Jackets",45
• "Hats",15
• must be written and read in consecutive order
• files can be created with NotePad and stored as
  .txt files

6
File Access Statements

• Open statement to open the file
• Input statement to read from the file
• Write or Print statement to write to the file
• Close statement to close the file

7
Open Statement

• Enables input/output (I/O) to a file.
• Open pathname For mode As filenumber
• Open a\Data.txt" For Input As 1

8
Input Statement

• Reads data from an open sequential file and
  assigns the data to variables.
• Syntax
• Input filenumber, varlist
• Example
• Input 1, strItem, intOrder

9
Write Statement

• Writes data to an open sequential file.
• Syntax
• Write filenumber, outputlist
• Example
• Write 1, strItem, intOrder

10
Print Statement

• Writes display-formatted data to an open
  sequential file.
• Print filenumber, outputlist
• Open a\data.txt" For Output As 1
• Print 1, "This is a test"
• Print 1, Spc(5) "5 leading spaces "
• Print 1, Hello Tab(10) World!

11
Close Statement

• Concludes input/output (I/O) to a file opened
  using the Open statement.
• Syntax
• Close filenumberlist
• Example
• Close 1
• If you omit filenumberlist, all active files
  opened by the Open statement are closed.