A C/C++ header for parsing and evaluation of arithmetic expressions.
[README file is almost identical to that of the ceval library]
| Function | Argument(s) | Return Value |
|---|---|---|
ceval_result() |
A mathematical expression in the form of a character array or a CPP string | The result of the expression as a floating point number |
ceval_tree() |
A mathematical expression in the form of a character array or a CPP string | The function prints the parse tree with each node properly indented depending on it's location in the tree structure |
Any valid combination of the following operators and functions, with floating point numbers (in decimal or exponential form) as operands can be parsed by ceval. Parentheses can be used to override the default operator precedences.
- Arithematic operators
+ (addition), - (subtraction), * (multiplication), / (division), % (modulo), ** (exponentiation), // (quotient)
- Relational operators
== (equal), != (not equal), < (strictly less), > (strictly greater), <= (less or equal), >= (greater or equal) to compare the results of two expressions
- Single-argument functions
exp(), sqrt(), cbrt(), sin(), cos(), tan(), asin(), acos(), atan(), sinh(), cosh(), tanh(), abs(), ceil(), floor(), log10(), ln(), deg2rad(), rad2deg(), signum(), int(), frac(), fact()
- Two-argument functions
pow(), atan2(), gcd(), hcf(), lcm(), log() (generalized log(b, x) to any base b)
- Pre-defined math constants
pi, e
...pre-defined constants are prefixed with an underscore
- Logical operators
&&, || and !
- Bitwise operators
&, |, ^, <<, >>, ~
-
Other operators
,(Comma operator) Comma operator returns the result of it's rightmost operand Ex:2,3would give3;4,3,0would be equal to0; andcos(pi/2,pi/3,pi)would returncos(pi)i.e,-1
Include 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
The inbuilt functions in ceval print out error messages to stdout when some syntactical anomaly is encountered during the parsing and evaluation process. To suppress the error messages, define the CEVAL_STOICAL macro before including the library in a C/C++ project. In the stoic mode, problematic expressions are evaluated to nan.
#define CEVAL_STOICAL
#include<ceval/ceval.h>
.
.
.
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