TOPS-20 PASCAL Language Manual - Bitsavers

PASCAL DATA TYPES
In addition to decimal notation, PASCAL allows you to specify integer
constants in binary, octal, and hexadecimal notation. You can use
constants written in these notations anywhere that decimal integer
constants are permitted.
To specify an integer constant in binary, octal, or hexadecimal
notation, place a percent sign (%) and a letter in front of a number
enclosed in apostrophes. The appropriate letters, which can be either
uppercase or lowercase, are B for binary notation, 0 for octal
notation, and X for hexadecimal notation. An optional plus or minus
sign can precede the percent sign to indicate a positive or negative
value. Note that regardless of which notation you use, the value can
not exceed MAXINT, for example:
-%B'111001'
%b'10000011'
%0'7712'
-%0'473'
+%X'53Al'
-%x'DEC'
2.2.1.2 REAL Data Type - The reserved words REAL, SINGLE, and DOUBLE
denote the real number types. In PASCAL, a real number can range from
+-0.14*10**-38 through +-3.4*10**38, with a typical precision of eight
decimal digits. REAL and SINGLE are synonymous; both have
single-precision real number va]ues. The type DOUBLE allows you to
declare double-precision real variables. You can assign real and
integer values to a variable of type REAL, SINGLE, or DOUBLE. If you
assign an integer value to a variable of type REAL, PASCAL converts
the integer to a real number.
In a PASCAL program, you can write real numbers in two ways; fixed on
floating point. With fixed point notation, you write the number with
the decimal point exactly where it appears in the value. The first
way is the following form:
2.4
893.2497
-0.01
8.0
-23.18
0.0
Note that, in this form, at least one digit must appear on each side
of the decimal point. That is, a zero must always precede the decimal
point of a number between 1 and -1, and a zero must follow the decimal
point of a whole number.
Some numbers, however, are too large or too small to write
conveniently in the above format. PASCAL provides scientific (also
known as exponential) notation as a second way of writing real
numbers. In scientific notation, you write the number as a positive
or negative value followed by an exponent, for example:
2.3E2
-0.07E4
10.0E-1
-201E+3
-2.14159£0
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