INSTRREV

• Source: https://www.freebasic.net/wiki/wikka.php?wakka=KeyPgInstrrev
• Last revised: 2025-08-29

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Locates the last occurrence of a substring or character within a string

Syntax

declare function Instrrev ( byref str as const string, [ Any ] byref substring as const string, byval start as integer = -1 ) as integer
declare function Instrrev ( byref str as const wstring, [ Any ] byref substring as const wstring, byval start as integer = -1 ) as integer

Usage

` last = Instrrev( str, [ Any ] substring [, start ] )

`

Parameters

str

The string where to search.

substring

The substring to find.

start

The position in str at which the search will begin. The first character starts at position 1.

Return Value

The position of the last occurrence of substring in str.

Description

Locates the position of the last occurrence of a substring or character within a string. If start parameter is not given or is less than zero, the search begins at the last character.

Zero (0) is returned if:

• substring is not found, or
• either str or substring is an empty strings, or
• start is zero, or
• start is greater than the length of str.

If the Any keyword is specified, Instrrev returns the last occurrence of any character in substring.

Examples

start GeSHi

' It will return 4
Print INSTRREV("abcdefg", "de")

' It will return 0
Print INSTRREV("abcdefg", "h")

end GeSHi

start GeSHi

Dim test As String
Dim idx As Integer

test = "abababab"
idx = instrrev(test, "b")

Do While idx > 0 'if not found loop will be skipped
    Print """b"" at " & idx
    idx = instrrev(Test, "b", idx - 1)
Loop

end GeSHi

'A Unicode example:

dim text as wstring*20

text = "Привет, мир!"

print instrrev(text,"ет") ' displays 5

Platform Differences

• The wide-character string version of Instrrev is not supported for DOS target.

Dialect Differences

• Not available in the -lang qb dialect unless referenced with the alias __Instrrev.

Differences from QB

• New to FreeBASIC

See also

• Instr
• Mid (Function)

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