Input Function
Reads data from an open sequential file and assigns the data to variables.
Public Sub Input( _
FileNumber As Integer, _
ByRef Value As Object _
)
Parameters
FileNumber
Required. Any valid file number.Value
Required. Variable that is assigned the values read from the file—cannot be an array or object variable.
Exceptions
Exception type |
Error number |
Condition |
|---|---|---|
FileNumber does not exist. |
||
File mode is invalid. |
See the "Error number" column if you are upgrading Visual Basic 6.0 applications that use unstructured error handling. (You can compare the error number against the Number Property (Err Object).) However, when possible, you should consider replacing such error control with Structured Exception Handling Overview for Visual Basic.
Remarks
The Input function is provided for backward compatibility and may have an impact on performance. For non-legacy applications, the My.Computer.FileSystem object provides better performance. For more information, see File Access with Visual Basic.
Data read with Input is usually written to a file with Write. Use this function only with files opened in Input or Binary mode.
.gif "Security note") Security Note: |
|---|
When reading from files, do not make decisions about the contents of the file based on the file name extension. For example, a file named Form1.vb may not be a Visual Basic source file. |
When read, standard string or numeric data is assigned to variables without modification. The following table illustrates how other input data is treated.
Data |
Value assigned to variable |
|---|---|
Delimiting comma or blank line |
Empty |
#NULL# |
DBNull |
#TRUE# or #FALSE# |
True or False |
#yyyy-mm-ddhh:mm:ss# |
The date and/or time represented by the expression |
#ERROR errornumber# |
errornumber (variable is an object tagged as an error) |
If you reach the end of the file while you are inputting a data item, the input is terminated and an error occurs.
Note
The Input function is not localized. For example, in the German version, if you input 3,14159, it returns only 3, since the comma is treated as a variable separator rather than a decimal point.
| Security Note: |
|---|
Reading from a file with the Input function requires Read access from the FileIOPermissionAccess enumeration. For more information, see FileIOPermissionAccess Enumeration. |
Example
This example uses the Input function to read data from a file into two variables. This example assumes that TestFile is a file with a few lines of data written to it using the Write function, each line containing a string in quotations and a number separated by a comma, for example: ("Hello", 234).
FileOpen(1, "TESTFILE", OpenMode.Output)
Write(1, "hello")
Write(1, 14)
FileClose(1)
Dim s As String = "teststring"
Dim i As Integer
FileOpen(1, "TESTFILE", OpenMode.Input)
Input(1, s)
MsgBox(s)
Input(1, i)
MsgBox(i)
FileClose(1)
Smart Device Developer Notes
This function is not supported.
Requirements
Namespace: Microsoft.VisualBasic
**Module:**FileSystem
Assembly: Visual Basic Runtime Library (in Microsoft.VisualBasic.dll)
See Also
Tasks
How to: Write Text to Files in Visual Basic
How to: Write Text to Files with a StreamWriter in Visual Basic