Subsections

• Arithmetic, logical and character string expressions
• Control statements
• Loops
• IF statements
• GOTO statements or GO
• CALL statement
• INCLUDE directive
• Other statements
• Input/output statements
• FORMAT statement
• INQUIRE statement
• INPUT statement or INP
• TYPE statement

Other language elements

Arithmetic, logical and character string expressions

The following operations are available:

    +  -  *  /  **  //
   .LT.   or   <
   .LE.   or   <=
   .EQ.   or   ==
   .NE.   or   /=
   .GE.   or   >=
   .GT.   or   >
   .OR.  .AND.  .NOT.

The logical operators .EQV. and .NEQV. are not included in COMIS.

Control statements

Loops

DO loops with index and DO WHILE (logical expression) constructions are provided. Loops may have the DO-ENDDO or DO-OD forms or may be labeled in a Fortran-like manner. For the indexed loops the index may be of an integer or a real type only.

IF statements

COMIS supports both the standard F77 syntax and a form ending in FI for the IF statement.      IF...[ELSEIF]...[ELSE]...ENDIF
or
     IF...[ELESIF]...[ELSE]...FI

GOTO statements or GO

Jumps to constant labels, assigned GOTOs in connection with ASSIGN statements, and computed GOTOs are provided.

F77 allows the use of a list with optional labels on an assigned GOTO statement; this facility is not supported in COMIS.

CALL statement

This statement calls a user or a COMIS routine.

COMIS supports three forms of the CALL statement:

  1.   CALL subr_name [( arg_list)]
  2.   subr_name ( arg_list)
  3.1  subr_name  arg_list
  3.2  subr_name;

where subr_name is the name of the subroutine which may be:

• an already defined COMIS routine;
• a user supplied routine: if no COMIS routine with the specified name is found, then COMIS will search for a user routines with that name (see also section 3.3).

The semi-colon character ``;'' is significant in case 3.2 above!

INCLUDE directive

An INCLUDE directive is available and has one of the following forms:

  1.   INCLUDE 'name'
  2.   INCLUDE  name
When name is given between quotes (case 1. above), then the name is taken literally, while in case 2. the string name is converted to uppercase.

Note that COMIS does not allow recursive INCLUDE directives.

Other statements

CONTINUE

the short form of this statement is CON

RETURN

the short form of this statement is RET

QUIT

return from COMIS to application program

END

the short form of this statement is ``#''

Input/output statements

The full set of F77 input/output statements is implemented. COMIS provides four types of input/output statements:

• Sequential input/output statements
• Direct access input/output statements
• List directed input/output statements
• Internal data set input/output statements.

A list of COMIS input/output source statements follows:  OPEN, WRITE, PRINT, READ, ENDFILE, BACKSPACE, REWIND, CLOSE, INQUIRE.
The COMIS extentions are:

• INPUT statement - input from a terminal in free format.
• TYPE statement - output to a terminal in free format.

FORMAT statement

The FORMAT statement has the form:  FORMAT( f1 [,f2 [,...,fn]])
where f1,f2,...,fn are format codes. The current version of COMIS does not support kP, S, SP, SS, BN and BZ edit descriptors.

The length of a format specification cannot exceed 256 characters.

INQUIRE statement

The INQUIRE statement has one of the forms:        INQUIRE(dsns,iflist)
       INQUIRE(  ns,iflist)

dsns

data set name specifier of the form FILE= dsn;

ns

data set reference number of the form UNIT= ns;

iflist

list as defined in Fortran 77.

You cannot omit UNIT=ns on a COMIS inquire statement.

INPUT statement or INP

The INPUT statement has the form      INPUT list
This statement inputs values from the terminal; the user is prompted with the list element name. If the user press a carriage return key, the current value is not changed, otherwise the constant typed in becomes the new value of a list element. If a list element value is a constant then this constant is simply typed out.

TYPE statement

The TYPE statement has the form      TYPE list
This statement types values of the lists elements in free format.

Example:

If the user runs the next simple COMIS program:        CHARACTER A*4
       J=1
       INPUT 'CHARACTER *4',A, 'J HAS VALUE 1',J,Z
       TYPE A,J,Z
       END
The dialogue will be 'CHARACTER*4'
*C  A=abcd<cr>
'J HAS VALUE 1'
*I  J=<cr>
*R  Z=3.14<cr>
*T  A = ABCD     J = 1     Z = 3.140000