The InStr Function

The InStr function returns the position of the first occurrence of one string within another.

The InStr function can return the following values:

• If string1 is "" - InStr returns 0
• If string1 is Null - InStr returns Null
• If string2 is "" - InStr returns start
• If string2 is Null - InStr returns Null
• If string2 is not found - InStr returns 0
• If string2 is found within string1 - InStr returns the position at which match is found
• If start > Len(string2) - InStr returns 0

Tip: Also look at the InStrRev function

Syntax

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

Example 1

dim txt,pos
txt="This is a beautiful day!"
pos=InStr(txt,"his")
document.write(pos)

Output:

2

Example 2

dim txt,pos
txt="This is a beautiful day!"
'A textual comparison starting at position 4
pos=InStr(4,txt,"is",1)
document.write(pos)

Output:

6

Example 3

dim txt,pos
txt="This is a beautiful day!"
'A binary comparison starting at position 1
pos=InStr(1,txt,"B",0)
document.write(pos)

Output:

0

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