String parsing of type @" 2 x (4 -1 ) = "

Question

I am attempting to parse a string of
NSString *multiplyString = @" 2 x (4 -1 ) = "
The problem that I am having is that I cannot separate 4( , or the -1. Hence, any characters that are touching each other. I used NSScanner to remove the blank spaces and store the resulting string values in a NSMutableArray.
BOOL fBlankSpaces = NO;
NSString *multiplyString = @" 2 x (4 -1 ) = "
NSString *gotItTrimmed = [[NSString alloc]init];
NSScanner *theScanner = [NSScanner scannerWithString:trimmedString];
NSMutableArray *sTrimmedValues = [NSMutableArray arrayWithCapacity:5];
while ([theScanner isAtEnd] == NO) {
fBlankSpaces = [theScanner scanUpToCharactersFromSet:[NSCharacterSet whitespaceCharacterSet] intoString:&gotItTrimmed];
if(fBlankSpaces == YES)
[sTrimmedValues addObject: gotItTrimmed];
Thanks for you help and suggestions!

Answer 1

T2TU wrote:
Thank you for your suggestions, but how do I convert it to "prefix notation" or "postfix notation"?
This is a classic programming problem everyone does (or should) in school. There are different ways to do it. This site has some good information. You should be able to find a few dozen other sites with similar instructions.
Why can't I store each character into an array, after the string is parsed, and then do a mathematical calculation on converted items?
Because you have to worry about parentheses, precedence, and associativity if you want to do it correctly. Plus, it is an excellent way to learn about trees and stacks.