How to: Search Within a String (Visual Basic) 

This example calls the IndexOf method on a String object to report the index of the first occurrence of a substring.

Example

Dim SearchWithinThis As String = "ABCDEFGHIJKLMNOP"
Dim SearchForThis As String = "DEF"
Dim FirstCharacter As Integer = SearchWithinThis.IndexOf(SearchForThis)

This code example is also available as an IntelliSense code snippet. In the code snippet picker, it is located in Data Types - defined by Visual Basic. For more information, see How to: Insert Snippets Into Your Code (Visual Basic).

Compiling the Code

This example requires:

• An Imports statement specifying the System namespace. For more information, see Imports Statement.

Robust Programming

The IndexOf method reports the location of the first character of the first occurrence of the substring. The index is 0-based, which means the first character of a string has an index of 0.

If IndexOf does not find the substring, it returns -1.

The IndexOf method is case-sensitive and uses the current culture.

For optimal error control, you might want to enclose the string search in the Try block of a Try...Catch...Finally Statement (Visual Basic) construction.

See Also

Reference

Try...Catch...Finally Statement (Visual Basic)
IndexOf

Other Resources

Introduction to Strings in Visual Basic
Search and Replace for Strings in Visual Basic