bc: About Expressions and Special Variables
3.1 About Expressions and Special Variables
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The numbers are manipulated by expressions and statements. Since the
language was designed to be interactive, statements and expressions are
executed as soon as possible. There is no main program. Instead, code
is executed as it is encountered. (Functions, discussed in detail
later, are defined when encountered.)
A simple expression is just a constant. 'bc' converts constants into
internal decimal numbers using the current input base, specified by the
variable IBASE. (There is an exception in functions.) The legal values
of IBASE are 2 through 36. (Bases greater than 16 are an extension.)
Assigning a value outside this range to IBASE will result in a value of
2 or 36. Input numbers may contain the characters 0-9 and A-Z. (Note:
They must be capitals. Lower case letters are variable names.) Single
digit numbers always have the value of the digit regardless of the value
of IBASE. (i.e. A = 10.) For multi-digit numbers, 'bc' changes all
input digits greater or equal to IBASE to the value of IBASE-1. This
makes the number 'ZZZ' always be the largest 3 digit number of the input
base.
Full expressions are similar to many other high level languages.
Since there is only one kind of number, there are no rules for mixing
types. Instead, there are rules on the scale of expressions. Every
expression has a scale. This is derived from the scale of original
numbers, the operation performed and in many cases, the value of the
variable SCALE. Legal values of the variable SCALE are 0 to the maximum
number representable by a C integer.
Info Catalog
bc: Expressions
bc: Expressions
bc: Basic Expressions