InStr Function

Returns the position of the first occurrence of one string within another.

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

Arguments

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

The following examples use InStr to search a string:

Dim SearchString, SearchChar, MyPos
SearchString ="XXpXXpXXPXXP"   ' String to search in.
SearchChar = "P"   ' Search for "P".
MyPos = Instr(4, SearchString, SearchChar, 1)   ' A textual comparison starting at position 4. Returns 6.
MyPos = Instr(1, SearchString, SearchChar, 0)   ' A binary comparison starting at position 1. Returns 9.    
MyPos = Instr(SearchString, SearchChar)   ' Comparison is binary by default (last argument is omitted). Returns 9.
MyPos = Instr(1, SearchString, "W")   ' A binary comparison starting at position 1. Returns 0 ("W" is not found).

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.

Requirements