Partager via


Left Function (Visual Basic) 

Returns a string containing a specified number of characters from the left side of a string.

Public Shared Function Left( _
   ByVal str As String, _
   ByVal Length As Integer _
) As String

Parameters

  • str
    Required. String expression from which the leftmost characters are returned.
  • Length
    Required. Integer expression. Numeric expression indicating how many characters to return. If 0, a zero-length string ("") is returned. If greater than or equal to the number of characters in str, the entire string is returned.

Exceptions

Exception type Error number Condition

ArgumentException

5

Length < 0.

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

To determine the number of characters in str, use the Len function. If used in a Windows Forms application, or any other class that has a Left property, you must fully qualify the function with Microsoft.VisualBasic.Left.

Note

The LeftB function in previous versions of Visual Basic returns a string in bytes rather than characters. It is used primarily for converting strings in double-byte character set (DBCS) applications. All current Visual Basic strings are in Unicode, and LeftB is no longer supported.

Example

This example demonstrates the use of the Left function to return a substring of a given String. In a class that has a Left property, it may be necessary to fully qualify the Left function.

Dim TestString As String = "Hello World!"
' Returns "Hello".
Dim subString As String = Microsoft.VisualBasic.Left(TestString, 5)

Requirements

Namespace: Microsoft.VisualBasic

Module: Strings

Assembly: Visual Basic Runtime Library (in Microsoft.VisualBasic.dll)

See Also

Reference

String Manipulation Summary
Right Function (Visual Basic)
Len Function (Visual Basic)
Mid Function (Visual Basic)
ArgumentException

Concepts

Programming Element Support Changes Summary