how to say if string contains in vba code example

Example 1: excel vba check if a string only contains letters

'VBA function to test if a string contains only letters:

Function IsAlpha(s) As Boolean
    IsAlpha = Len(s) And Not s Like "*[!a-zA-Z]*"
End Function

Example 2: excel vba string contains

Dim SearchString, SearchChar, MyPos
SearchString ="XXpXXpXXPXXP"    ' String to search in.
SearchChar = "P"    ' Search for "P".

' A textual comparison starting at position 4. Returns 6.
MyPos = Instr(4, SearchString, SearchChar, 1)    

' A binary comparison starting at position 1. Returns 9.
MyPos = Instr(1, SearchString, SearchChar, 0)

' Comparison is binary by default (last argument is omitted).
MyPos = Instr(SearchString, SearchChar)    ' Returns 9.

' Not found
MyPos = Instr(1, SearchString, "W")    ' Returns 0.