Questions about INSTR

[mdijkens]

Mid$ is extremely slow with larger strings (a lot of memcopy is going on)
Instr is extremely efficient in finding next hit in memory
Strings have a limit of 2GB max and since Instr only works on strings, the startpos and returnval are Long (-2G to +2G)
_Mem can handle size of your PC's RAM

Code: (Select All)

Const MAXSIZE = 2 ^ 31 - 1 '2GB



Dim a As String: a = String$(MAXSIZE, 0)

Asc(a, MAXSIZE) = 42

aa& = InStr(a, Chr$(42))

Print Len(a), InStr(a, Chr$(42)), aa&



Dim b As String * MAXSIZE

Asc(b, MAXSIZE) = 42

bb& = InStr(b, Chr$(42))

Print Len(b), InStr(b, Chr$(42)), bb&





Const MSIZE = MAXSIZE * 5 '10GB

Dim m As _MEM: m = _MemNew(MSIZE) '10GB

Dim c As String * 1: c = Chr$(42)

_MemPut m, m.OFFSET + MSIZE - 1, c

Print m.SIZE,

Dim block As String * MAXSIZE

For p&& = 0 To m.SIZE \ MAXSIZE

  b = _MemGet(m, m.OFFSET + p&& * MAXSIZE, String * MAXSIZE)

  mm& = InStr(b, c)

  If mm& Then Exit For

Next p&&

Print m.SIZE, p&& * MAXSIZE + mm&