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Overview of Pascal Extensions

A

This Appendix gives an overview of the Pascal extensions to ISO/ANSI standard Pascal.

Lexical Elements

Pascal supports the following extensions to the lexical elements of standard Pascal:

Uppercase- and lowercase-sensitive
The special symbols ~, &, |, !, #, and %
The reserved words external, otherwise, private, public, and univ
The reserved words define, extern, module, and static
The identifiers in Table A-1
An underscore (_) and dollar_sign($) in identifier names
The comment delimiters /* */. in addition to the standard (* *) and { }
The comment delimiters " "

Table A-1 Nonstandard Identifiers

Nonstandard Identifiers

`FALSE`

`close`

`index`

`lsr`

`return`

`TRUE`

`concat`

`integer16`

`max`

`rshft`

`addr`

`date`

`integer32`

`maxchar`

`seed`

`alfa`

`discard`

`intset`

`message`

`seek`

`append`

`double`

`land`

`min`

`shortreal`

`argc`

`exit`

`lastof`

`minchar`

`single`

`argv`

`expo`

`length`

`minint`

`sizeof`

`arshft`

`filesize`

`linelimit`

`next`

`stradd`

`asl`

`firstof`

`lnot`

`null`

`substr`

`asr`

`flush`

`longreal`

`open`

`tell`

`assert`

`getfile`

`lor`

`pack`

`trace`

`bell`

`getenv`

`lshft`

`random`

`trim`

`card`

`halt`

`lsl`

`remove`

`univ_ptr`

`clock`

`in_range`

Data Types

Pascal supports the following extensions to the standard Pascal data types:

The real data types shortreal and longreal
The real data types single and double
A real constant without a digit after the decimal point
The integer data types integer16 and integer32
An integer constant in another base
Character constants minchar, maxchar, bell, and tab
Fixed-length and variable-length character strings
Array initialization using a default upper bound or a repeat count
A set of type intset, which contains the elements 0 through 127
A pointer type to procedures and functions
A universal pointer type that holds a pointer to a variable of any data type

Statements

Pascal extends the standard definition of statements, as follows:

The and then and or else operators in the if statement
The assert statement
The otherwise statement in a case statement
Constant ranges in a case statement
The exit statement in a for, while, or repeat loop
The next statement in a for, while, or repeat loop
An identifier as the target of a goto statement
The return statement in a procedure or function
An alternative format of the with statement

Assignments and Operators

Pascal supports the following extensions to standard Pascal operators:

The bitwise operators ~(not), &(and), |(or), and !(or)
The boolean operators and then and or else
The relational operators on sets
The equality (=) and inequality <> ) ( operators on records and arrays
The concatenation operator, the plus sign (+), on any combination of fixed- and variable-length strings

Headings and Declarations

Pascal supplies the following extensions to the standard program heading and declarations:

Identifiers as labels
A constant equal to a set expression
public and private variable declarations
The static, extern, and define variable attributes
real, integer, boolean, character, set, record, array, and pointer variable initialization in the var declaration
The define declaration
The label, const, type, var, and define declaration in any order and any number of times

Procedures and Functions

Pascal supports the following extensions to the standard Pascal definition of procedures and functions:

public and private procedure and function declarations
The in, in out, and out parameter types
The univ keyword parameter type
The extern, external, internal, variable, and nonpascal routine options
Functions returning structured types

Built-In Routines

Pascal supports the following nonstandard built-in routines:

The addr function, which returns the address of a specified variable
The append procedure, which opens a file for writing at its end
The argc function, which returns the number of arguments passed to the program
The argv procedure, which assigns the specified program argument to a string variable
The arshft function, which does an arithmetic right shift of an integer
The asl function, which does an arithmetic left shift of an integer
The asr function, which is identical to arshft
The concat function, which concatenates two strings
The card function, which returns the cardinality of a set
The clock function, which returns the user time used by the process
The close procedure, which closes the specified file
The date procedure, which fetches the current date
The discard procedure, which explicitly discards the return value of a function
The expo function, which calculates the exponent of a specified variable
The filesize function, which returns the current size of a file
The firstof function, which returns the first possible value of a type or variable
The flush procedure, which writes the output buffered for the specified Pascal file into the associated operating system file
The getenv function, which returns the value associated with an environment name
The getfile function, which returns a pointer to the C standard I/O descriptor associated with the specified Pascal file
The halt procedure, which terminates program execution
The index function, which returns the position of the first occurrence of a string or character within another string
The in_range function, which determines whether a specified value is in the defined integer subrange
The land function, which returns the bitwise and of two integer values
The lastof function, which returns the last possible value of a type or variable
The length function, which returns the length of a string
The linelimit function, which terminates execution of a program after a specified number of lines have been written into a text file
The lnot function, which returns the bitwise not of an integer value
The lor function, which returns the inclusive or of two integer values
The lshft function, which does a logical left shift of an integer
The lsl function, which is identical to lshft
The lsr function, which is identical to rshft
The max function, which returns the larger of two expressions
The message procedure, which writes the specified information to stderr
The min function, which returns the smaller of two expressions
The null procedure, which performs no operation
The open procedure, which associates an external file with a file variable
The random function, which generates a random number between 0.0 and 1.0
The read and readln procedures, which read in boolean variables, fixed- and variable-length strings, enumerated types, and pointers from the standard input
The remove procedure, which removes the specified file
The reset and rewrite procedures, which accept an optional second argument, a Solaris 2.0 operating system file name
The rshft function, which does a logical right shift of an integer
The seed function, which reseeds the random number generator
The seek procedure, which resets the current position of a file
The sizeof function, which returns the size of a specified type, variable, constant, or string
The stlimit procedure, which terminates program execution if a specified number of statements have been executed in the current loop
The stradd procedure, which adds a string to the end of another string
The substr function, which extracts a substring from a string
The sysclock function, which returns the system time used by the process
The tell function, which returns the current position of a file
The time procedure, which retrieves the current time
The trace procedure, which prints stack traceback
The trim function, which removes the trailing blanks in a character string
The type_transfer function, which changes the data type of a variable or expression
The wallclock function, which returns the elapsed number of seconds since 00:00:00 GMT January 1, 1970
The write and writeln procedures, which output enumerated type values to the standard output and allow output expressions in octal or hexadecimal
The write and writeln procedures, which allow negative field widths
The xor function, which returns the exclusive or of two integer values

Input and Output

Pascal supports the following extensions to standard Pascal input and output:

Association of a Pascal file with either a permanent or temporary Solaris operating system file
The special predefined file variables, input and output, that need not be specified in the program statement
The special predefined file variable, errout
An I/O error recovery mechanism

Program Compilation

Pascal supports the following extensions to program compilation:

Sharing variable, procedure, and function declarations across multiple units using include files
Sharing variable, procedure, and function declarations across multiple units using multiple declarations
Sharing variable, procedure, and function declarations across multiple units using the extern and define variable declarations
Sharing variable, procedure, and function declarations between units of different languages using the extern and external routine options

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