Punataro Puhn Chaturaphit Punataro Puhn Chaturaphit - 5 months ago 21
Objective-C Question

Convert NSString of a math equation to a value

I would like to know how to evaluate a string representation of an equation as if it were a real equation:

if(@"15+14==23")
{
//True statement...
}
else
{
//False statement....
}


I want to return "false" because 15+14 does not equal 23. How can I get this to work?

Answer

Here is an example how to do it with NSPredicate:

NSPredicate *p = [NSPredicate predicateWithFormat:@"1+2==3"];
NSLog(@"%d", [p evaluateWithObject:nil]);
p = [NSPredicate predicateWithFormat:@"1+2==4"];
NSLog(@"%d", [p evaluateWithObject:nil]);

The first NSLog produces 1 because 1+2==3 is true; the second produces 0.