VBScript in a Nutshell, 2nd Edition

Name

Mid, MidB Functions

Syntax

Mid(string, start[, length])

string

Use: Required

Data Type: String

The expression from which to return a substring.

start

Use: Required

Data Type: Long

The starting position of the substring.

length

Use: Optional

Data Type: Long

The length of the substring.

Return Value

A String.

Description

Returns a substring of a specified length from within a given string.

Rules at a Glance

• If string contains a Null, Mid returns Null.

• If start is more than the length of string, a zero-length string is returned.

• If start is less than zero, error 5, “Invalid procedure call or argument,” is generated.

• If length is omitted or is greater than the length of string, all characters from start to the end of string are returned.

• The MidB version of the Mid function is used with byte data held within a string. When using MidB, both start and length refer to numbers of bytes as opposed to numbers of characters.

Example

The following example is a function that parses a string passed to it as a parameter and writes each word to a dynamic array. Note the use of the InStr function to determine the position of a space, which in this case is the character that can terminate a word:

Public Function ParseString(strString) Dim arr( ) Dim intStart, intEnd, intStrLen, intCtr intCtr = 0 intStart = 1 intStrLen = Len(strString) Redim Preserve arr(10) Do While intStart > 0 intEnd = InStr(intStart, strString, " ") - 1 If intEnd <= 0 Then intEnd = intStrLen If intCtr > UBound(arr) Then Redim Preserve arr(UBound(arr)+10) ...