Built-in functions and procedures

Modula-2 also makes available several built-in procedures and functions. In describing these, the following metavariables are used:

a

represents an ARRAY variable.

c

represents a CHAR constant or variable.

i

represents a variable or constant of integral type.

m

represents an identifier that belongs to a set. Generally used in the same function with the metavariable s. The type of s should be SET OF mtype (where mtype is the type of m).

n

represents a variable or constant of integral or floating-point type.

r

represents a variable or constant of floating-point type.

t

represents a type.

v

represents a variable.

x

represents a variable or constant of one of many types. See the explanation of the function for details.

All Modula-2 built-in procedures also return a result, described below.

ABS(n)

Returns the absolute value of n.

CAP(c)

If c is a lower case letter, it returns its upper case equivalent, otherwise it returns its argument.

CHR(i)

Returns the character whose ordinal value is i.

DEC(v)

Decrements the value in the variable v by one. Returns the new value.

DEC(v,i)

Decrements the value in the variable v by i. Returns the new value.

EXCL(m,s)

Removes the element m from the set s. Returns the new set.

FLOAT(i)

Returns the floating point equivalent of the integer i.

HIGH(a)

Returns the index of the last member of a.

INC(v)

Increments the value in the variable v by one. Returns the new value.

INC(v,i)

Increments the value in the variable v by i. Returns the new value.

INCL(m,s)

Adds the element m to the set s if it is not already there. Returns the new set.

MAX(t)

Returns the maximum value of the type t.

MIN(t)

Returns the minimum value of the type t.

ODD(i)

Returns boolean TRUE if i is an odd number.

ORD(x)

Returns the ordinal value of its argument. For example, the ordinal value of a character is its ASCII value (on machines supporting the ASCII character set). x must be of an ordered type, which include integral, character and enumerated types.

SIZE(x)

Returns the size of its argument. x can be a variable or a type.

TRUNC(r)

Returns the integral part of r.

VAL(t,i)

Returns the member of the type t whose ordinal value is i.

Warning: Sets and their operations are not yet supported, so treats the use of procedures INCL and EXCL as an error.

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