Here is one more IsNumber() procedure
Should accept all known numeric formats (i hope it is bug free, though not 100% sure as always
) despite all the tests as you can see below, so please if you find any bug, let me know, thanks 
Code: Select all
EnableExplicit
Procedure My_IsNumber(txt.s)
; sign +/- : is accepted at the begining or after e (begining <=> prv = 0)
; dot . : is accepted anywhere but once only
; exp e : is validated if preceeded by a digit and ( followed by a digit or followed by a sign digit)
; A valid number will have its ValD() correct
;
Protected cur.c, prv.c, *p.Character, i, n, nbr_dot, nbr_exp, vld_exp, nbr_dgt
n = Len(txt)
If n = 0 : ProcedureReturn #False : EndIf
For i=1 To n
prv = cur
*p = @txt + (i-1) * SizeOf(Character)
cur = *p\c
Select cur
Case '+', '-'
If (prv <> 'e') And (prv <> 0) : ProcedureReturn #False : EndIf
Case '.'
nbr_dot + 1
If nbr_exp > 0 : ProcedureReturn #False : EndIf
Case 'e'
If (prv = '.') Or ((prv >= '0') And (prv <= '9'))
nbr_exp + 1
vld_exp = -1 ; an 'e' has started
Else
ProcedureReturn #False
EndIf
Case '0' To '9'
If vld_exp = -1 : vld_exp + 1 : EndIf ; closing started 'e' if any
nbr_dgt + 1
Default
ProcedureReturn #False
EndSelect
If (nbr_dot > 1) Or (nbr_exp > 1) : ProcedureReturn #False : EndIf
Next
If vld_exp <> 0 : ProcedureReturn #False : EndIf
If nbr_dgt <= 0 : ProcedureReturn #False : EndIf
ProcedureReturn #True
EndProcedure
Procedure Test_IsNumber(txt.s)
If My_IsNumber(txt)
Debug "[" + txt + "] ..... is a Valid Number .... ValD = " + StrD(ValD(txt))
Else
Debug "[" + txt + "] ..... is NOT a Valid Number .... ValD = " + StrD(ValD(txt))
EndIf
EndProcedure
Debug "--------- No Valid Number ------------"
Test_IsNumber("")
Test_IsNumber("a")
Test_IsNumber("+")
Test_IsNumber("123a")
Test_IsNumber("a123")
Test_IsNumber("e4")
Test_IsNumber("4e")
Test_IsNumber("4ee1")
Test_IsNumber("++41")
Test_IsNumber("--41")
Test_IsNumber("+4+")
Test_IsNumber("+4-")
Test_IsNumber("-4+")
Test_IsNumber("-4e")
Test_IsNumber("+4e")
Test_IsNumber("4e.3")
Test_IsNumber("4e.-3")
; ----
Debug "--------- Valid Number ------------"
Test_IsNumber("0")
Test_IsNumber("123")
Test_IsNumber("12.3")
Test_IsNumber("0.0123")
Test_IsNumber(".123")
Test_IsNumber("4e0")
Test_IsNumber("4e2")
Test_IsNumber("2.1e1")
Test_IsNumber("2.1e-1")
Test_IsNumber("2.1e+1")
Test_IsNumber("0.1e1")
Test_IsNumber("0.1e0")
Test_IsNumber("0.1e-1")
Test_IsNumber("0.1e+1")
Test_IsNumber("0.1e0")
Test_IsNumber(".1e1")
Test_IsNumber(".1e-1")
Test_IsNumber(".1e+1")
Test_IsNumber(".1e0")
Test_IsNumber("+0")
Test_IsNumber("+123")
Test_IsNumber("+12.3")
Test_IsNumber("+0.0123")
Test_IsNumber("+.123")
Test_IsNumber("+4e0")
Test_IsNumber("+4e2")
Test_IsNumber("+2.1e1")
Test_IsNumber("+2.1e-1")
Test_IsNumber("+2.1e+1")
Test_IsNumber("+0.1e1")
Test_IsNumber("+0.1e0")
Test_IsNumber("+0.1e-1")
Test_IsNumber("+0.1e+1")
Test_IsNumber("+0.1e0")
Test_IsNumber("+.1e1")
Test_IsNumber("+.1e-1")
Test_IsNumber("+.1e+1")
Test_IsNumber("+.1e0")
Test_IsNumber("-0")
Test_IsNumber("-123")
Test_IsNumber("-12.3")
Test_IsNumber("-0.0123")
Test_IsNumber("-.123")
Test_IsNumber("-4e0")
Test_IsNumber("-4e2")
Test_IsNumber("-2.1e1")
Test_IsNumber("-2.1e-1")
Test_IsNumber("-2.1e+1")
Test_IsNumber("-0.1e1")
Test_IsNumber("-0.1e0")
Test_IsNumber("-0.1e-1")
Test_IsNumber("-0.1e+1")
Test_IsNumber("-0.1e0")
Test_IsNumber("-.1e1")
Test_IsNumber("-.1e-1")
Test_IsNumber("-.1e+1")
Test_IsNumber("-.1e0")
