Convert "(scaleValue<0.5)?(4.5*data1):(1.5*data2)" to double value

Hello,

I would like to convert "(scaleValue<0.5)?(4.5*data1) : (1.5*data2)" to double value with following assumptions,

scaleValue = 1.5;
data1 = 2.0;
data2 = 4.0;

I would like to convert the above string and return result as double value. How to do this?

Regards,
Sankar.

There is no string in any of the expressions above. Do your assignments in the branch statements.

I mean the expression is stored in a string as given below,
QString strData = "(scaleValue<0.5)?(4.5*data1) : (1.5*data2)";

I would like to evaluate the expression and returns its resultant value.


Regards,
Sankar.

You already named it - you need an expression evaluator :-)
Search the internet for Scanner, Parser, expression evaluation. Depending on the functionality you need, this can become quite complex - http://www.arstdesign.com/articles/e...valuation.html gives you an idea. For sure there are expression evaluators in C/C++ available on the internet which you can start with and adjust to your needs.

Regards,
Andreas

Code:

---

QString strData = "(scaleValue<0.5)?(4.5*data1) : (1.5*data2)";
QScriptEngine engine;
QScriptValue result = engine.evaluate(strData);
qreal resultDouble = result.toNumber(); // or qscriptvalue_cast<qreal>(result);

---

Thanks Wysota.

Will try to make use of this.

Regards,
Sankar.