| Mid, MidB Statements |
Named Arguments
No
Syntax
Mid(stringvar, start[, length]) = string
stringvar
Use: Required
Data Type: String
The name of the string variable to be modified.
start
Use: Required
Data Type: Variant (Long)
The position within stringvar at which the replacement commences.
length
Use: Optional
Data Type: Variant (Long)
The number of characters in stringvar to replace.
string
Use: Required
Required: String
The string that replaces characters within stringvar.
Description
Replaces a section of a string with characters from another string.
Rules at a Glance
If you omit length, as many characters of string as can be fitted into stringvar are used.
If start + length is greater then the length of stringvar, string is truncated to fit in the same space as stringvar. This means that the length of stringvar isn't altered by the Mid statement.
If start is less than 0, runtime error 5, "Invalid procedure call or argument," occurs.
The MidB version of the Mid statement is used with byte data held within a string. When using MidB, both start and length refer to the number of bytes, as opposed to the number of characters.
Programming Tips and Gotchas
If string contains Null, runtime error 94, "Invalid Use of Null," is generated.
VB6 includes the Replace function, which enhances the functionality of the Mid statement by allowing you to specify the number of times the replacement is carried out in the same string.
Although the documentation refers to Mid when it appears on the left side of an assignment statement as a statement and on the right side as a function, you may find it easier to remember their purpose and syntax if you consider both variations as functions. In the second case, stringvar is passed to the function by value, and therefore it isn't modified by the function itself, which returns the substring desired. In the first case, stringvar is passed to the function by reference, so that, when the function returns, its value is modified accordingly.