COBOL: Limitations and Deficiencies Julian Stacey,

Introduction

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Grace Hopper of the US Navy in 1959 -~ historically Cobol was the second high
level (non-assembler) language (the first being FORTRAN (FORmula TRANslation)
for scientific applications). Cobol was a significant development

Cobol, (COmmon Bu

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CoboL, (LUmmon Susiness

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but is now considered 23 years later in 1982, to have inherent deficiencies in
many areas, despite the efforts of the ANSI Cobol Committee to enhance this
product of the 'punched card and valve computer' era.

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of source code, all of which has to be both initially typed in, and 1
read by maintenance programmers.

2
Cobol is an insufficiently structured language with a considerable number of
eccentricities, the cumulative effect of which is to make programs harder to

uctured programming; attempts by

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'structured' result in even more occurences of the (justly
' statement, making the resultant code less structrued.

2.2

GOTOs : An excess number of 'GOTO's necessitates a high number of labels,

programmers are thus forced to invent a large number of label names and usually
come up with label names meaningless to future maintenance programmers and
current design colleagues.

2.3

Constructs

Cobol compilers allow the following dangerous constructs :-

PERFORM A THROUGH B
A: some statements ...

GOTO C

[>)

where B and C can be anywhere in the program.

Whilst most procedural languages will allow a programmer 'GOTO's if um
by the programmer, they are often 'warned of' by the compiler, (particularly
if it goes more than one level in or out), furthermore as GOTOs form such
potentially dangerous constructs; they immediately leap to the programmer's
eye when checking for errors, whereas in Cobol an erroreous GOTO is not easily
seen, hidden amongst all the normal 's; — this point becomes more significant
after initial program development, when the project enters a maintenance and

update/amendment phase.

PERFORM A THROUGH B VARYING X FROM 12 BY 6 UNTIL X GREATER THAN 3

A ceen
GOTO C
GOTO D

B: csesscane

can be much better replaced by a typical algorithmic language comstruct such as:-—

e
BOAATNITRT A
K.

< +5 o 5 Z ITamTT v [} AT T
FOR X = 12 STEP 6 UNTIL X )| 73 CALL PROCEDURE A

2.4
Cobol has obscure 'magic' numbers of deep significance: data division declaraticms
must be proceeded by a level number ranging from 0 to 80, some are special reserved

a
numbers, some are not; those that are special are:-—

Level 0 & 1) Special significance to some, but not all compilers
* 8) Normal outermost statements
77) Automatic switches such as 'PASS VALUES ARE 8 THROUGH 10'
88) Constants

Numbers on an inner level must have a higher number than all outer levels. When
a piece of source text is moved or copied (using an editor) to a new place in
the program, it is thus often necessary to renumber many lines, further it is
interesting to speculate what would happen if many levels of nesting were required,
in excess of 69 (=77-8).

2.5
The comment delimiter in different program divisions varies between:
'REMARK', & 'NOTE' this lack of uniformity is unimportant; but is synonymous of

LMARK Lacx rtant, but

other irregularities.

3
Cobol lacks a number of the facilities of newer language, facilities such as:-

3.1
cal variable that can only be a

. 1o rag 5 e Drogram
not the rest of th YOgYr

ond calling procedure cannot call a target procedure until the first calling
procedure has finished, else the variable values will be overwritten. Cobol 1is
thus both not re-entrant and not recursive.

3.2.2

Stacks rely on dynamic allocs
non-expandable beyond a finite point.
3.3

As no ASCII string passing is available, dynamic file or structure pointing
becomes impossible, except by time consuming chaining through every possible
element in a list of things possible to point at, or by jumping to an assembler
routine written in another language: neither of which expedient would be

outset.
*

3.4
Data typing is limited:-
3.4.1
There are only a limited number of data types in Cobol:-—
1 Alpha and Alpha Numeric ASCII fixed length character arrays.
Numerics (stored in ASCII)

umer

2
3 1Integers (Computational)

3.4.2
The following data types found in most scientific engineering languages are not
available in Cobol:-

Signed and Unsigned Integers;

Short, Normal and Long Integers;

Floating Point and Double Floating Point;

Pointers to all other data types, including pointers to pointers.
Arrays of " " " "oy, " arrays of arrays.

3.4

Sefel

Unlike Cobol newer languages like Pascal, Ada, and Chill allow a user to specify
data types of their own, ie. in Pascal:-

TYPE workday = (monday, tuesday, wednesday, thursday, friday saturday, sunday)
VAR holiday, workday: day;

although Cobol can specify a list, or boundary limits of acceptable values that
may be assigned to a variable, what Cobol cannot do is check that a variable of
the right type is being allocated to a variable. (Thus Cobol could allow 'Granny
h' as an assigmment to an employee-name field, whereas it might be of type
ety', and thus would be rejected at compile time by Pascal.

s appropriate for applications involvlng little real processing, but a lot
of copying, some semi-automatic sorting, and prec1se output formatting, clyp.l.J.LdLJ.uub
such as payroll cheque printing are typical. Though some salesmen claim many of
their 'systems programs' are written in Cobol, in fact their definition of a 'systems
program' is generally very loose, and often covers system environment scftware
seen by a user; on closer investigation Cobol is found to be totally inappropriate
for true kernel systems design programming, and is not used statements such as
"if Cobol is used for a system supplier's own software it must be good enough for

our applications" are thus erroneous

st Cobol programmers are plentiful in commercial data processing environments,
ol experience is less often found in engineering staff, who are more likely to
have skills in procedural languages such as Algol, PLl, Pascal, €, PL/M & PL/Z,
Coral, Chill, Ada and TAL. Cobol (and Basic) applications programmers are the
least skilled, lowest paid ptogrammers in computing, a disproportionate number of
databases use Cobol only because first simple database requirements were in the DP
world, but now databases are becoming more complex (relational instead of hierarchic
etc.), and fast interactive response times are becoming required instead of batch
usage, the ratio of Cobol databases is decreasing, with the advent of many database

management systems written in modern languages.

= check if allways valid