InStr Function

Returns a Variant (Long) specifying the position of the first occurrence of one string within another.

Syntax

InStr([start, ]string1, string2[, compare])

The InStr function syntax has these arguments:

Part Description
start Optional. Numeric expression that sets the starting position for each search. If omitted, search begins at the first character position. If start contains Null, an error occurs. The start argument is required if compare is specified.
string1 Required. String expression being searched.
string2 Required. String expression sought.
compare Optional. Specifies the type of string comparison. If compare is Null, an error occurs. If compare is omitted, the Option Compare setting determines the type of comparison. Specify a valid LCID (LocaleID) to use locale-specific rules in the comparison.

Settings

The compare argument settings are:

Constant Value Description
vbUseCompareOption -1 Performs a comparison using the setting of the Option Compare statement.
vbBinaryCompare 0 Performs a binary comparison.
vbTextCompare 1 Performs a textual comparison.
vbDatabaseCompare 2 Microsoft Access only. Performs a comparison based on information in your database.

Return Values

If InStr returns
string1 is zero-length 0
string1 is Null Null
string2 is zero-length start
string2 is Null Null
string2 is not found 0
string2 is found within string1 Position at which match is found
start > string2 0

Remarks

The InStrB function is used with byte data contained in a string. Instead of returning the character position of the first occurrence of one string within another, InStrB returns the byte position.

Example

This example uses the InStr function to return the position of the first occurrence of one string within another.

Dim SearchString, SearchChar, MyPos
SearchString ="XXpXXpXXPXXP"    ' String to search in.
SearchChar = "P"    ' Search for "P".

' A textual comparison starting at position 4. Returns 6.
MyPos = Instr(4, SearchString, SearchChar, 1)    

' A binary comparison starting at position 1. Returns 9.
MyPos = Instr(1, SearchString, SearchChar, 0)

' Comparison is binary by default (last argument is omitted).
MyPos = Instr(SearchString, SearchChar)    ' Returns 9.

MyPos = Instr(1, SearchString, "W")    ' Returns 0.
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