InStr Function

Microsoft® Visual Basic® Scripting Edition
InStr Function

Description

Returns 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 searched for.

compare Optional. Numeric value indicating the kind of comparison to use when evaluating substrings. See Settings section for values. If omitted, a binary comparison is performed.

Settings

The compare argument can have the following values:

Constant Value Description

vbBinaryCompare 0 Perform a binary comparison.

vbTextCompare 1 Perform a textual comparison.

Return Values

The InStr function returns the following 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 > Len(string2) 0

Remarks

Note 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.

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 searched for.
compare	Optional. Numeric value indicating the kind of comparison to use when evaluating substrings. See Settings section for values. If omitted, a binary comparison is performed.

Constant	Value	Description
vbBinaryCompare	0	Perform a binary comparison.
vbTextCompare	1	Perform a textual comparison.

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 > Len(string2)	0


Note 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.