Task: IBAN

C: #include <alloca.h>
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define V(cc, exp) if (!strncmp(iban, cc, 2)) return len == exp


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

    return 0;
}


int strip(char *s)
{
    int i = -1, m = 0;

    while(s[++i]) {
        s[i - m] = s[i];
        m += s[i] <= 32;
    }

    s[i - m] = 0;
    return i - m;
}


int mod97(const char *s, int len)
{
    int i, j, parts = len / 7;
    char rem[10] = "00";

    for (i = 1; i <= parts + (len % 7 != 0); ++i) {
        strncpy(rem + 2, s + (i - 1) * 7, 7);
        j = atoi(rem) % 97;
        rem[0] = j / 10 + '0';
        rem[1] = j % 10 + '0';
    }

    return atoi(rem) % 97;
}

int valid_iban(char *iban)
{
    int i, j, l = 0, sz = strip(iban);
    char *rot, *trans;

    
    for (i = 0; i < sz; ++i) {
        if (!isdigit(iban[i]) && !isupper(iban[i]))
            return 0;
        l += !!isupper(iban[i]);
    }

    if (!valid_cc(iban, sz))
        return 0;

    
    rot = alloca(sz);
    strcpy(rot, iban + 4);
    strncpy(rot + sz - 4, iban, 4);

    
    trans = alloca(sz + l + 1);
    trans[sz + l] = 0;

    
    for (i = j = 0; i < sz; ++i, ++j) {
        if (isdigit(rot[i]))
            trans[j] = rot[i];
        else {
            trans[j]   = (rot[i] - 55) / 10 + '0';
            trans[++j] = (rot[i] - 55) % 10 + '0';
        }
    }

    return mod97(trans, sz + l) == 1;
}

int main(int _, char **argv)
{
    while (--_, *++argv)
        printf("%s is %svalid.\n", *argv, valid_iban(*argv) ? "" : "in");

    return 0;
}









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.