lokicalc

Můj zápočtový prográmek na /Programování I s Jakubem Bystroněm.

Zadání a o co jde

Kalkulačka s dlouhými čísly. Dlouhá čísla mě moc nebrala, takže žádné vychytané násobení. Zato ale podoruje všechny možné unární, postfixové, zprava asociativní apod. operátory, proměnné. Součástí je generátor jednoprůchodového tokenizeru.

Z README

DESCRIPTION

lokicalc is an interactive calculator with arbitrarily long integers. Stress has been put rather on flexibility and future expandability than on the efficiency of operations.


NUMBERS

Numbers have to be integer. Some operations require numbers to be small, this is by default smaller than 10000. Divisors, powers and operands for a factorial have to be small. In other context numbers of any length are allowed.


VARIABLES

Variables can contain numbers. Uninitialized variables contain zero. Variables can be used as lvalues (assigned to, incremented, decremented).


COMMENTS

C-style comments are allowed anywhere where a whitespace can be. They are however not allowed to span multiple lines in the interactive mode (which is currently the only mode supported).


EXPRESSIONS

Expressions are similar to C expressions. They consists of base-10 numbers, variables, operators, parentheses (and whitespaces between any two of these).

- expr       Negation of the expression.
+ expr       The expression (identity, just for symmetry).
++ var       Preincrementation as in C.
var ++       Postincrementation as in C.
-- var       Predecrementation as in C.
var --       Postdecrementation as in C.
expr + expr  Sum of the two expressions.
expr - expr  Difference of the two expressions.
expr * expr  Product of the two expressions.
expr / expr  Integer part of the quotient of the two expressions.
expr % expr  Remainder after division of the two expressions.
expr ^^ expr The first expression raised to the second.
expr !       Factorial of expr.
( expr )     Parentesised expression (alters precedence).
var = expr   Assignment (returns value of the expression).
expr, expr   Value of the second expression (both are evaluated).

expr1 <  expr2  1 if expr is strictly less than expr2, else 0.
expr1 <= expr2  1 if expr is less than or equal to expr2, else 0.
expr1 == expr2  1 if expr is equal to expr2, else 0.
expr1 >= expr2  1 if expr is greater than or equal to expr2, else 0.
expr1 >  expr2  1 if expr is strictly greater than expr2, else 0.
expr1 != expr2  1 if expr is not equal to expr2, else 0.

!expr         1 if expr is 0.
expr && expr  1 if both expressions are non-zero (short evaluation).
expr || expr  1 if either expression is non-zero (short evaluation).

The expression precedence (lowest to highest):
,           binary, left associative
=           binary, right associative
||          binary, left associative
&&          binary, left associative
== !=       binary, left associative
< <= >= >   binary, left associative
+ -         binary, left associative
* / %       binary, left associative
^^          binary, right associative
- + ! ++ -- unary,  right associative
            (As if postfix operators had higher precedence, like in C.)

IMPORTANT: -1^^2 is therefore +1. However, this is common (bc, Excel).


STATEMENTS

Statement can be either an expression or the command "quit" which causes lokicalc to exit.


TECHNICAL INFORMATION

Output is first tokenized using a tokenization code generated with LCTokenTool. Token definitions supported by LCTokenTool allow for simple recursive definitions and partially overlapping unambiguous definitions, for instance:

 - operators like + and ++, =, !, !=, ==
 - C-style identifiers
 - numbers (0 is allowed, but 025 or 00 is not)
 - whitespace including C-style comments (/* ... */)

Unknown token errors may happen during tokenization.

Expressions are then parsed into trees based only on the knowledge of operator precedence, associativity and being binary/prefix/postfix. Parse errors are caught.

Expression is then evaluated, possibly causing side effects (assignment, incrementation, decrementation of a variable). Semantic errors can appear (zero division etc.).

See the source code for more information.


COMPATIBILITY

The code violates the ANSI C90 with declarations mixed with statements. This is the only violation of standards. It requires gcc 3.0 or later to compile successfully.

Stažení

file:lokicalc.tar.gz — tarball 23 KB, asi 3.5 k řádků kódu.

Matfiz : AdamNohejl/lokicalc

lokicalc

Zadání a o co jde

Z README

Stažení