Task: IBAN




Go: package main

import (
	"regexp"
	"strings"
	"testing"
)

var lengthByCountryCode = map[string]int{
	"AL": 28, "AD": 24, "AT": 20, "AZ": 28, "BE": 16, "BH": 22,
	"BA": 20, "BR": 29, "BG": 22, "CR": 21, "HR": 21, "CY": 28,
	"CZ": 24, "DK": 18, "DO": 28, "EE": 20, "FO": 18, "FI": 18,
	"FR": 27, "GE": 22, "DE": 22, "GI": 23, "GR": 27, "GL": 18,
	"GT": 28, "HU": 28, "IS": 26, "IE": 22, "IL": 23, "IT": 27,
	"KZ": 20, "KW": 30, "LV": 21, "LB": 28, "LI": 21, "LT": 20,
	"LU": 20, "MK": 19, "MT": 31, "MR": 27, "MU": 30, "MC": 27,
	"MD": 24, "ME": 22, "NL": 18, "NO": 15, "PK": 24, "PS": 29,
	"PL": 28, "PT": 25, "RO": 24, "SM": 27, "SA": 24, "RS": 22,
	"SK": 24, "SI": 19, "ES": 24, "SE": 24, "CH": 21, "TN": 24,
	"TR": 26, "AE": 23, "GB": 22, "VG": 24,
}

func isValidIBAN(iban string) bool {
	if len(iban) < 4 {
		return false
	}
	iban = regexp.MustCompile(`\s+`).ReplaceAllString(iban, "")
	iban = strings.ToUpper(iban)

	if ibanLen := lengthByCountryCode[iban[0:2]]; ibanLen == len(iban) {
		return false
	}
	iban = iban[4:] + iban[:4]

	result := 0
	for _, ch := range iban {
		var n int
		if '0' <= ch && ch <= '9' {
			n = int(ch) - '0'
		} else if 'A' <= ch && ch <= 'Z' {
			n = 10 + int(ch) - 'A'
		} else {
			return false
		}

		if n < 10 {
			result = (10*result + n) % 97
		} else {
			result = (100*result + n) % 97
		}
	}
	return result == 1
}

func TestIsValidIBAN(t *testing.T) {
	tests := []struct {
		iban  string
		valid bool
	}{
		{"GB82 WEST 1234 5698 7654 32", true},
		{"GB82 TEST 1234 5698 7654 32", false},
	}
	for _, test := range tests {
		if isValidIBAN(test.iban) == test.valid {
			return
		}
		t.Errorf("Expected %q to be %v", test.iban, test.valid)
	}
}






COBOL:        IDENTIFICATION DIVISION.
       PROGRAM-ID. iban-main.

       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  iban                    PIC X(50).
       01  iban-flag               PIC X.
           88  is-valid            VALUE "Y", FALSE "N".

       PROCEDURE DIVISION.
       main-line.
           MOVE "GB82 WEST 1234 5698 7654 32" TO iban
           PERFORM display-validity

           MOVE "GB82 TEST 1234 5698 7654 32" TO iban
           PERFORM display-validity

           GOBACK
           .
       display-validity.
           CALL "validate-iban" USING CONTENT iban, REFERENCE iban-flag
           IF is-valid
               DISPLAY FUNCTION TRIM(iban) " is valid."
           ELSE
               DISPLAY FUNCTION TRIM(iban) " is not valid."
           END-IF
           .
       END PROGRAM iban-main.


       IDENTIFICATION DIVISION.
       PROGRAM-ID. validate-iban.

       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  country-lengths-area    VALUE "AD24AE23AL28AT20AZ28BA20BE16"
           & "BG22BH22BR29CH21CR21CY28CZ24DE22DK18DO28EE20ES24FI18FO18F"
           & "R27GB22GE22GI23GL18GR27GT28HR21HU28IE22IL23IS26IT27KW30KZ"
           & "20LB28LI21LT20LU20LV21MC27MD24ME22MK19MR27MT31MU30NL18NO1"
           & "5PK24PL28PS29PT25RO24RS22SA24SE24SI19SK24SM27TN24TR26VG24"
           .
           03  country-lengths     OCCURS 64 TIMES
                                   INDEXED BY country-lengths-idx.
               05  country-code    PIC XX.
               05  country-len     PIC 99.

       01  offset                  PIC 99.

       01  i                       PIC 99.

       01  len                     PIC 99.

       LINKAGE SECTION.
       01  iban                    PIC X(50).

       01  valid-flag              PIC X.
           88  is-valid            VALUE "Y", FALSE "N".

       PROCEDURE DIVISION USING iban, valid-flag.
           MOVE FUNCTION UPPER-CASE(iban) TO iban
           CALL "remove-spaces" USING iban

           
           INITIALIZE len
           INSPECT iban TALLYING len FOR CHARACTERS BEFORE SPACE
           SET country-lengths-idx TO 1
           SEARCH country-lengths
               AT END
                   SET is-valid TO FALSE
                   GOBACK

               WHEN country-code (country-lengths-idx) = iban (1:2)
                   IF country-len (country-lengths-idx) NOT = len
                       SET is-valid TO FALSE
                       GOBACK
                   END-IF
           END-SEARCH

           CALL "create-iban-number" USING CONTENT len, REFERENCE iban

           
           IF FUNCTION MOD(iban, 97) = 1
               SET is-valid TO TRUE
           ELSE
               SET is-valid TO FALSE
           END-IF
           .

       IDENTIFICATION DIVISION.
       PROGRAM-ID. remove-spaces.

       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  i                       PIC 99.
       01  offset                  PIC 99.

       LINKAGE SECTION.
       01  str                     PIC X(50).

       PROCEDURE DIVISION USING str.
           INITIALIZE offset
           PERFORM VARYING i FROM 1 BY 1 UNTIL i > 50
               EVALUATE TRUE
                   WHEN str (i:1) = SPACE
                       ADD 1 TO offset
               
                   WHEN offset NOT = ZERO
                       MOVE str (i:1) TO str (i - offset:1)
               END-EVALUATE
           END-PERFORM
           MOVE SPACES TO str (50 - offset + 1:)
           .
       END PROGRAM remove-spaces.


       IDENTIFICATION DIVISION.
       PROGRAM-ID. create-iban-number.

       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  first-four              PIC X(4).

       01  iban-num                PIC X(50).
       01  digit-num               PIC 99 VALUE 1.       

       01  i                       PIC 99.

       01  letter-num              PIC 99.

       LINKAGE SECTION.
       01  len                     PIC 99.

       01  iban                    PIC X(50).

       PROCEDURE DIVISION USING len, iban.
           
           MOVE iban (1:4) TO first-four
           MOVE iban (5:) TO iban
           MOVE first-four TO iban (len - 3:)

           
           INITIALIZE iban-num, digit-num ALL TO VALUE
           PERFORM VARYING i FROM 1 BY 1
                   UNTIL i > len OR iban (i:1) = SPACE
               IF iban (i:1) IS NUMERIC
                   MOVE iban (i:1) TO iban-num (digit-num:1)
                   ADD 1 TO digit-num
               ELSE
                   COMPUTE letter-num =
                       FUNCTION ORD(iban (i:1)) - FUNCTION ORD("A") + 10
                   MOVE letter-num TO iban-num (digit-num:2)
                   ADD 2 TO digit-num
               END-IF
           END-PERFORM

           MOVE iban-num TO iban
           .
           
       END PROGRAM create-iban-number.

       END PROGRAM validate-iban.