How do you search for a string in a file in VB?

Answer 1

This is a simple function which will read the file line by line and search each individual line until the target string is found, then return the line number it was found in. It will return zero if the string was not found.

This is a simple function whipped up to demonstrate the basic technique, it has not been debugged or tested at all, and is certainly not the best solution possible. It also lacks any form of error trapping/handling.

You should not use this code in any program intended for production without rewriting it.

public function FindStringInFile(byval strTarget as string) as long

Dim iFile as integer 'file number

Dim iLineNum as long 'counter for line number

Dim strTmp as string 'variable length string to hold string from file

Dim bFound as boolean 'flag to indicate it was found

'First, open the file for input:

iFile = freefile 'get the next free file number

open "filename.txt" for input as #iFile 'open the file in input mode

do until eof(ifile) 'continue reading lines until the end of the file

line input #ifile, strTmp 'read a line into the string variable iLineNum = iLineNum + 1 'increment the line number counter

if instr$(strTarget, strTmp) <> 0 then 'set the flag and exit the loop

bFound = true

exit do

end if

loop

'check the flag

if bFound then

'found, return the line number

FindStringInFile = iLineNum

else

'not found, return zero

FindStringInFile = 0

end if

end function