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A simple command line calculator

Posted 16 years ago

How many times have you needed to calculate something, for example the value of 0x398A3BB, so you pop up windows calculator to convert it? I did lots of times. The problem is I hate to use the mouse. It takes precious deciseconds away from software development time to remove my hands from the keyboard and use the mouse. That's why I created calc.exe. Its a simple command line calculator (and its also an example of recursive decent parsing).

Download calc.exe
Download calc.c

Examples

C:>calc 5+5*5
30.000000

c:>calc 0x30
48.000000

c:>calc (123456 % 51)/12
3.000000

Steve Hanov makes a living working on Rhymebrain.com, rapt.ink, www.websequencediagrams.com, and Zwibbler.com. He lives in Waterloo, Canada.

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Matt

two years ago

RE: Yolo's request in the comments. I made some small changes in S.Hanov's excellent calc.c code that may meet your needs and use is almost daily (on Windows 10). A copy of that code is at: github.com/mccright/ccalc

Thank you again, Steve Hanov!

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yolo

three years ago

Can somebody fix the debug output and post it somewhere?

thx

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Smith

four years ago

0x30 isn't "0 times 30". For that you would input 0*30.

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ProDigit

four years ago

you can do the same in python.

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Code55

eleven years ago

Any ways to remove the debug output mentionned by Kosenkov?

"Apparently you've forgotten to remove debug output:

C:>calc 10*4

parse_expr()

parse_term()

parse_factor()

parse_num_op()

parse_rest_term()

parse_factor()

parse_num_op()

parse_rest_term()

parse_rest_expr()

40.000000

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A Kosenkov

twelve years ago

Apparently you've forgotten to remove debug output:

C:>calc 10*4

parse_expr()

parse_term()

parse_factor()

parse_num_op()

parse_rest_term()

parse_factor()

parse_num_op()

parse_rest_term()

parse_rest_expr()

40.000000

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Marc Lepage

13 years ago

If you install cygwin for a Unix-like environment on Windows (bash shell and all the basic tools) then you have more options. You can use the built in expr (expression) command as a simple calculator. Or write a simple script to use Google's calculator (perhaps via Lynx or curl).

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Mario

13 years ago

Or you could, you know use a "real operating system" and not have to re-invent UNIX poorly :D.

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Simon Sapin

14 years ago

The parser example is interesting, but for a command line calculator I use this: (in ~/.bashrc)

calc() {

python -c "from math import *; print $*"

}

Example:

$ calc pi - 3

0.14159265359

This, or one of the ipython shells I have lying around.

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smallbug 2

15 years ago

oops

it seems that the replacement i did have effect on A ^ 9 expression...

the replacement should be :

resolve_variable(val);

if ( match_char( '^' ) ){

val_t val2;

parse_num_op( &val2 );

val->d.fval = pow( val->d.fval, val2.d.fval );

parse_rest_num_op( val );

}

parse_rest_expr( val );

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Small bug in the code !

15 years ago

Your code does not take in count expression like :

myVariable + 1

This is due to a bug in the void parse_rest_var function !

The following code solve this problem and seems to not have boundary effect !

void parse_rest_var( val_t* val )

{

if ( match_char( '=' ) ) {

val_t vexp;

parse_expr( &vexp );

if ( vexp.type != TYPE_FLOAT ) {

printf("Error: Tried to assign non-number to %s.\n", val->d.variable );

longjmp( env, 1 );

}

printf("Assigned to %s: ", val->d.variable );

map_add( val->d.variable, vexp.d.fval );

*val = vexp;

} else {

// -----------------------replace

// parse_rest_num_op( val );

// -- by

resolve_variable(val);

parse_rest_expr( val );

// ------------------End of modif !

}

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