How to convert condition text to "if" conditional expression?

Question

I'm trying to write in visual c++ to convert a condition text to a simple "if" conditional expression with arithmetic operators, parentheses.

For exemple : text : "(((a+b)>0)or(c==10))and(d!=e))" or "(a>b)xor(c==d)", etc...

we have normally in c++ style :

int a,b,c,d,e;
...
...    
char text[]="(((a+b)>0)or(c==10))and(d!=e))";
if(text_to_if(text)) { .... }
...
...

letters a, b, c, d, e in text correspond with existing integer or float variables.

There's no such thing like evaluating expressions at runtime in c++. — πάντα ῥεῖ, Jan 27 '19 at 11:52
Right, of course. But in fact, my objective is to make a function to translate this condition text to execute "real" conditions. I'm studying. — Chrisoft, Jan 27 '19 at 12:31
I think this is duplicate with [Evaluating arithmetic expressions from string in C++](https://stackoverflow.com/questions/9329406/evaluating-arithmetic-expressions-from-string-in-c#27442993) — Benoît Bottemanne, Jan 27 '19 at 12:39
@Chrisoft Closest I can think of is writing an expression parser e.g. using `boost::spirit`or similar. — πάντα ῥεῖ, Jan 27 '19 at 14:01

score 0 · Answer 1 · answered Jan 27 '19 at 12:26

Please mind that C++ is not an interpreted language. You can not change code, including if statements, at runtime. If you want runtime code evaluation you could try JavaScript with its eval() function 1.

Further on you won't be able to retrieve variable names from your code (except for debugging purposes).

How to convert condition text to "if" conditional expression?

1 Answers1