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FileSystem.LineInput(Int32) Method

  • Reference

Definition

Namespace:
Microsoft.VisualBasic
Assembly:
Microsoft.VisualBasic.Core.dll
Assembly:
Microsoft.VisualBasic.dll
Source:
FileSystem.vb
Source:
FileSystem.vb
Source:
FileSystem.vb

Reads a single line from an open sequential file and assigns it to a String variable.

C# 
public static string LineInput(int FileNumber);

Parameters

FileNumber
Int32

Required. Any valid file number.

Returns

String

Reads a single line from an open sequential file and assigns it to a String variable.

Exceptions

EndOfStreamException

End of file reached.

IOException

FileNumber does not exist.

Examples

This example uses the LineInput function to read a line from a sequential file and assign it to a variable. This example assumes that TestFile is a text file that has several lines of sample data.

VB 
Dim TextLine As String
' Open file.
FileOpen(1, "TESTFILE", OpenMode.Input)
' Loop until end of file.
While Not EOF(1)
    ' Read line into variable.
    TextLine = LineInput(1)
    ' Print to the console.
    Console.WriteLine("1", TextLine)
End While
FileClose(1)

Remarks

The LineInput function is provided for backward compatibility and may affect 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 LineInput is usually written to a file by using Print.

Important

When reading from files, do not make decisions about the contents of a file based on the file name extension. For example, a file that is named Form1.vb may not be a Visual Basic source file.

The LineInput function reads from a file one character at a time until it encounters a carriage return (Chr(13)) or carriage return/line feed (Chr(13) + Chr(10)) sequence. Carriage return/line feed sequences are skipped instead of appended to the character string.

Important

Reading from a file by using the LineInput function requires Read access from the FileIOPermissionAccess enumeration.

Applies to

Product Versions
.NET Core 3.0, Core 3.1, 5, 6, 7, 8, 9, 10
.NET Framework 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1

See also