Skip site navigation (1)Skip section navigation (2)

FreeBSD Man Pages

Man Page or Keyword Search:
Man Architecture
Apropos Keyword Search (all sections) Output format
home | help
DC(1)                   FreeBSD General Commands Manual                  DC(1)

NAME
       dc - an arbitrary precision calculator

SYNOPSIS
       dc [-V] [--version] [-h] [--help]
          [-e scriptexpression] [--expression=scriptexpression]
          [-f scriptfile] [--file=scriptfile]
          [file ...]

DESCRIPTION
       Dc is a reverse-polish desk calculator which supports unlimited
       precision arithmetic.  It also allows you to define and call macros.
       Normally dc reads from the standard input; if any command arguments are
       given to it, they are filenames, and dc reads and executes the contents
       of the files before reading from standard input.  All normal output is
       to standard output; all error output is to standard error.

       A reverse-polish calculator stores numbers on a stack.  Entering a
       number pushes it on the stack.  Arithmetic operations pop arguments off
       the stack and push the results.

       To enter a number in dc, type the digits with an optional decimal
       point.  Exponential notation is not supported.  To enter a negative
       number, begin the number with ``_''.  ``-'' cannot be used for this, as
       it is a binary operator for subtraction instead.  To enter two numbers
       in succession, separate them with spaces or newlines.  These have no
       meaning as commands.

OPTIONS
       Dc may be invoked with the following command-line options:

       -V

       --version
              Print out the version of dc that is being run and a copyright
              notice, then exit.

       -h

       --help Print a usage message briefly summarizing these command-line
              options and the bug-reporting address, then exit.

       -e script

       --expression=script
              Add the commands in script to the set of commands to be run
              while processing the input.

       -f script-file

       --file=script-file
              Add the commands contained in the file script-file to the set of
              commands to be run while processing the input.

       If any command-line parameters remain after processing the above, these
       parameters are interpreted as the names of input files to be processed.
       A file name of - refers to the standard input stream.  The standard
       input will processed if no file names are specified.

Printing Commands
       p      Prints the value on the top of the stack, without altering the
              stack.  A newline is printed after the value.

       n      Prints the value on the top of the stack, popping it off, and
              does not print a newline after.

       P      Pops off the value on top of the stack.  If it it a string, it
              is simply printed without a trailing newline.  Otherwise it is a
              number, and the integer portion of its absolute value is printed
              out as a "base (UCHAR_MAX+1)" byte stream.  Assuming that
              (UCHAR_MAX+1) is 256 (as it is on most machines with 8-bit
              bytes), the sequence KSK 0k1/ [_1*]sx d0>x [256~aPd0<x]dsxx
              sxLKk could also accomplish this function, except for the side-
              effect of clobbering the x register.

       f      Prints the entire contents of the stack without altering
              anything.  This is a good command to use if you are lost or want
              to figure out what the effect of some command has been.

Arithmetic
       +      Pops two values off the stack, adds them, and pushes the result.
              The precision of the result is determined only by the values of
              the arguments, and is enough to be exact.

       -      Pops two values, subtracts the first one popped from the second
              one popped, and pushes the result.

       *      Pops two values, multiplies them, and pushes the result.  The
              number of fraction digits in the result depends on the current
              precision value and the number of fraction digits in the two
              arguments.

       /      Pops two values, divides the second one popped from the first
              one popped, and pushes the result.  The number of fraction
              digits is specified by the precision value.

       %      Pops two values, computes the remainder of the division that the
              / command would do, and pushes that.  The value computed is the
              same as that computed by the sequence Sd dld/ Ld*- .

       ~      Pops two values, divides the second one popped from the first
              one popped.  The quotient is pushed first, and the remainder is
              pushed next.  The number of fraction digits used in the division
              is specified by the precision value.  (The sequence SdSn lnld/
              LnLd% could also accomplish this function, with slightly
              different error checking.)

       ^      Pops two values and exponentiates, using the first value popped
              as the exponent and the second popped as the base.  The fraction
              part of the exponent is ignored.  The precision value specifies
              the number of fraction digits in the result.

       |      Pops three values and computes a modular exponentiation.  The
              first value popped is used as the reduction modulus; this value
              must be a non-zero number, and should be an integer.  The second
              popped is used as the exponent; this value must be a non-
              negative number, and any fractional part of this exponent will
              be ignored.  The third value popped is the base which gets
              exponentiated, which should be an integer.  For small integers
              this is like the sequence Sm^Lm%, but, unlike ^, this command
              will work with arbitrarily large exponents.

       v      Pops one value, computes its square root, and pushes that.  The
              precision value specifies the number of fraction digits in the
              result.

       Most arithmetic operations are affected by the ``precision value'',
       which you can set with the k command.  The default precision value is
       zero, which means that all arithmetic except for addition and
       subtraction produces integer results.

Stack Control
       c      Clears the stack, rendering it empty.

       d      Duplicates the value on the top of the stack, pushing another
              copy of it.  Thus, ``4d*p'' computes 4 squared and prints it.

       r      Reverses the order of (swaps) the top two values on the stack.

Registers
       Dc provides at least 256 memory registers, each named by a single
       character.  You can store a number or a string in a register and
       retrieve it later.

       sr     Pop the value off the top of the stack and store it into
              register r.

       lr     Copy the value in register r and push it onto the stack.  This
              does not alter the contents of r.

       Each register also contains its own stack.  The current register value
       is the top of the register's stack.

       Sr     Pop the value off the top of the (main) stack and push it onto
              the stack of register r.  The previous value of the register
              becomes inaccessible.

       Lr     Pop the value off the top of register r's stack and push it onto
              the main stack.  The previous value in register r's stack, if
              any, is now accessible via the lr command.

Parameters
       Dc has three parameters that control its operation: the precision, the
       input radix, and the output radix.  The precision specifies the number
       of fraction digits to keep in the result of most arithmetic operations.
       The input radix controls the interpretation of numbers typed in; all
       numbers typed in use this radix.  The output radix is used for printing
       numbers.

       The input and output radices are separate parameters; you can make them
       unequal, which can be useful or confusing.  The input radix must be
       between 2 and 16 inclusive.  The output radix must be at least 2.  The
       precision must be zero or greater.  The precision is always measured in
       decimal digits, regardless of the current input or output radix.

       i      Pops the value off the top of the stack and uses it to set the
              input radix.

       o      Pops the value off the top of the stack and uses it to set the
              output radix.

       k      Pops the value off the top of the stack and uses it to set the
              precision.

       I      Pushes the current input radix on the stack.

       O      Pushes the current output radix on the stack.

       K      Pushes the current precision on the stack.

Strings
       Dc can operate on strings as well as on numbers.  The only things you
       can do with strings are print them and execute them as macros (which
       means that the contents of the string are processed as dc commands).
       All registers and the stack can hold strings, and dc always knows
       whether any given object is a string or a number.  Some commands such
       as arithmetic operations demand numbers as arguments and print errors
       if given strings.  Other commands can accept either a number or a
       string; for example, the p command can accept either and prints the
       object according to its type.

       [characters]
              Makes a string containing characters (contained between balanced
              [ and ] characters), and pushes it on the stack.  For example,
              [foo]P prints the characters foo (with no newline).

       a      The top-of-stack is popped.  If it was a number, then the low-
              order byte of this number is converted into a string and pushed
              onto the stack.  Otherwise the top-of-stack was a string, and
              the first character of that string is pushed back.

       x      Pops a value off the stack and executes it as a macro.  Normally
              it should be a string; if it is a number, it is simply pushed
              back onto the stack.  For example, [1p]x executes the macro 1p
              which pushes 1 on the stack and prints 1 on a separate line.

       Macros are most often stored in registers; [1p]sa stores a macro to
       print 1 into register a, and lax invokes this macro.

       >r     Pops two values off the stack and compares them assuming they
              are numbers, executing the contents of register r as a macro if
              the original top-of-stack is greater.  Thus, 1 2>a will invoke
              register a's contents and 2 1>a will not.

       !>r    Similar but invokes the macro if the original top-of-stack is
              not greater than (less than or equal to) what was the second-to-
              top.

       <r     Similar but invokes the macro if the original top-of-stack is
              less.

       !<r    Similar but invokes the macro if the original top-of-stack is
              not less than (greater than or equal to) what was the second-to-
              top.

       =r     Similar but invokes the macro if the two numbers popped are
              equal.

       !=r    Similar but invokes the macro if the two numbers popped are not
              equal.

       ?      Reads a line from the terminal and executes it.  This command
              allows a macro to request input from the user.

       q      exits from a macro and also from the macro which invoked it.  If
              called from the top level, or from a macro which was called
              directly from the top level, the q command will cause dc to
              exit.

       Q      Pops a value off the stack and uses it as a count of levels of
              macro execution to be exited.  Thus, 3Q exits three levels.  The
              Q command will never cause dc to exit.

Status Inquiry
       Z      Pops a value off the stack, calculates the number of digits it
              has (or number of characters, if it is a string) and pushes that
              number.

       X      Pops a value off the stack, calculates the number of fraction
              digits it has, and pushes that number.  For a string, the value
              pushed is 0.

       z      Pushes the current stack depth: the number of objects on the
              stack before the execution of the z command.

Miscellaneous
       !      Will run the rest of the line as a system command.  Note that
              parsing of the !<, !=, and !> commands take precedence, so if
              you want to run a command starting with <, =, or > you will need
              to add a space after the !.

       #      Will interpret the rest of the line as a comment.

       :r     Will pop the top two values off of the stack.  The old second-
              to-top value will be stored in the array r, indexed by the old
              top-of-stack value.

       ;r     Pops the top-of-stack and uses it as an index into the array r.
              The selected value is then pushed onto the stack.

       Note that each stacked instance of a register has its own array
       associated with it.  Thus 1 0:a 0Sa 2 0:a La 0;ap will print 1, because
       the 2 was stored in an instance of 0:a that was later popped.

BUGS
       Email bug reports to bug-dc@gnu.org.

GNU Project                       1997-03-25                             DC(1)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | Printing Commands | Arithmetic | Stack Control | Registers | Parameters | Strings | Status Inquiry | Miscellaneous | BUGS

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=dc&sektion=1&manpath=Red+Hat+Linux%2fi386+9>

home | help