A C/C++ header for parsing and evaluation of arithmetic expressions.
[README file is almost identical to that of the ceval library]
Any valid combination of the following operators and functions, with floating point numbers as operands can be parsed by ceval. Parentheses can be used to override the default operator precedences.
+ (addition), - (subtraction), * (multiplication), / (division), % (modulo), ** (exponentiation), // (quotient)
== (equal), != (not equal), < (strictly less), > (strictly greater), <= (less or equal), >= (greater or equal) to compare the results of two expressions
exp(), sqrt(), cbrt(), sin(), cos(), tan(), asin(), acos(), atan(), sinh(), cosh(), tanh(), abs(), ceil(), floor(), log10(), ln(), deg2rad(), rad2deg(), signum(), int(), frac(), fact()
pow(), atan2(), gcd(), hcf(), lcm(), log() (generalized log(b, x) to any base b)
_pi, _e
...pre-defined constants are prefixed with an underscore
&&, || and !
&, |, ^, <<, >>, ~
Other operators
, (Comma operator) Comma operator returns the result of it's rightmost operand Ex: 2,3 would give 3; 4,3,0 would be equal to 0; and cos(_pi/2,_pi/3,_pi) would return cos(_pi) i.e, -1e (e-operator for scientific notation) Using the binary e operator, we can use scientific notation in our arithmetic expressions Ex: 0.0314 could be written as 3.14e-2; 1230000 could be subsituted by 1.23e6Include the ceval library using the #include "PATH_TO_CEVAL.H" directive your C/C++ project.
The code snippet given below is a console based interpreter that interactively takes in math expressions from stdin, and prints out their parse trees and results.
//lang=c
#include<stdio.h>
#include<stdlib.h>
#include "ceval.h"
int main(int argc, char ** argv) {
char expr[100];
while (1) {
printf("In = ");
fgets(expr, 100, stdin);
if (!strcmp(expr, "exit\n")) {
break;
} else if (!strcmp(expr, "clear\n")) {
system("clear");
continue;
} else {
ceval_tree(expr);
printf("\nOut = %f\n\n", ceval_result(expr));
}
}
return 0;
}
In = 3*7**2
2
**
7
*
3
Out = 147.000000
In = (3.2+2.8)/2
2
/
2.80
+
3.20
Out = 3.000000
In = _e**_pi>_pi**_e
2.72
**
3.14
>
3.14
**
2.72
Out = 1.000000
In = 5.4%2
2
%
5.40
Out = 1.400000
In = 5.4//2
2
//
5.40
Out = 2.000000
In = 2*2.0+1.4
1.40
+
2
*
2
Out = 5.400000
In = (5/4+3*-5)+(sin(_pi))**2+(cos(_pi))**2
2
**
3.14
cos
+
2
**
3.14
sin
+
5
-
*
3
+
4
/
5
Out = -12.750000
In = 3,4,5,6
6
,
5
,
4
,
3
Out = 6.000000
In = tanh(2/3)==(sinh(2/3)/cosh(2/3))
3
/
2
cosh
/
3
/
2
sinh
==
3
/
2
tanh
Out = 1.000000
In = (2+3/3+(3+9.7))
9.70
+
3
+
3
/
3
+
2
Out = 15.700000
In = sin(_pi/2)+cos(_pi/2)+tan(_pi/2)
2
/
3.14
tan
+
2
/
3.14
cos
+
2
/
3.14
sin
[ceval]: tan() is not defined for odd-integral multiples of _pi/2
Out = nan
In = asin(2)
2
asin
[ceval]: Numerical argument out of domain
Out = nan
In = exit
... Program finished with exit code 0
When the ceval.h file is included in a C-program, you might require the -lm flag to link math.h
gcc file.c -lm