Convert NSString of a math equation to a value

前端 未结 3 546
温柔的废话
温柔的废话 2020-12-11 04:37

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...
}
els         


        
3条回答
  •  情歌与酒
    2020-12-11 05:25

    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.

提交回复
热议问题