Data commit

Task/Validate-International-Securities-Identification-Number/XPL0/validate-international-securities-identification-number.xpl0

@@ -0,0 +1,53 @@
+string 0;               \use zero-terminated strings
+
+func    Luhn(Str);      \Return 'true' if digits in Str pass Luhn test
+char    Str;
+int     Len, Sum, I, Dig;
+[Len:= 0;               \find length of Str
+while Str(Len) do Len:= Len+1;
+Sum:= 0;                \sum even and odd digits
+for I:= 0 to Len-1 do   \(no need to reverse)
+        [if (I xor Len) & 1 then
+                Sum:= Sum + Str(I) - ^0
+        else    [Dig:= Str(I) - ^0;
+                Dig:= Dig*2;
+                Sum:= Sum + Dig/10 + rem(0);
+                ];
+        ];
+return rem(Sum/10) = 0;
+];      \Luhn
+
+func    Valid(Str);     \Return 'true' if valid ISIN code
+char    Str, Str2(100);
+int     Sum, I, J, C, V;
+[J:= 0;
+for I:= 0 to 12-1 do    \convert letters in Str to digits in Str2
+        [C:= Str(I);
+        case of
+          C>=^0 & C<=^9: [Str2(J):= C;  J:= J+1];
+          C>=^A & C<=^Z: [Str2(J):= (C-^A+10)/10 + ^0;  J:= J+1;
+                          Str2(J):= rem(0) + ^0;  J:= J+1]
+        other return false;
+        if I=1 & J#4 then return false; \first two chars not letters
+        ];
+if Str(I) # 0 then return false;        \too long
+Str2(J):= 0;            \terminate string
+return Luhn(Str2);
+];      \Valid
+
+int     ISIN, N;
+[ISIN:= ["US0378331005",
+         "US0373831005",
+         "U50378331005",
+         "US03378331005",
+         "AU0000XVGZA3",
+         "AU0000VXGZA3",
+         "FR0000988040"];
+for N:= 0 to 7-1 do
+        [Text(0, ISIN(N));
+         Text(0, if Valid(ISIN(N))
+                then " is valid"
+                else " is not valid");
+        CrLf(0);
+        ];
+]