Compare two strings and remove common elements

Question

I have two comma seperated NSString 's & I want to remove the similar characters from first string only.

ex. str1 = 0,1,2,3
    str2 = 1,2.
    output -> str1 = 0,3 and str2 = 1,2.

I have one option that, seperate both the string with comma seperated values in a array. But it requires two NSArray 's & apply loop and then remove the common elements, but it is very tedious job. So I want some simple & proper solution which avoid the looping.

kindly help me to sort out this.

Answer 1

Try this one:

No loop is required!!!

You have got all the required APIs.

NSString *str1=@"0,1,2,3";
NSString *str2=@"1,2";

NSMutableArray *arr1=[[NSMutableArray alloc]initWithArray:[str1 componentsSeparatedByString:@","]];

[arr1 removeObjectsInArray:[str2 componentsSeparatedByString:@","]];
NSLog(@"arr1 %@",arr1);
/*
NSMutableString *finalString=[NSMutableString new];

for (NSInteger i=0; i<[arr1 count]; i++) {
    NSString *str=[arr1 objectAtIndex:i];

    [finalString appendString:str];
    if (i!=[arr1 count]-1) {
      [finalString appendString:@","];  
    }
}
*/
NSString *finalString=[arr1 componentsJoinedByString:@","];
NSLog(@"finalString %@",finalString);

Answer 2

Something like that ?

 NSString *string = @"0,1,2,3";
 NSPredicate *predicate = [NSPredicate predicateWithFormat:@"self like '1' OR self like '2'"];
 NSLog(@"%@",[[string componentsSeparatedByString:@","] filteredArrayUsingPredicate:predicate]);

Answer 3

    id str1=@"aa,ab,ac,cd,ce,cf";
    id str2=@"aa,ac,cd,cf";
    //no ab and no ce

    id cmps1 = [str1 componentsSeparatedByString:@","];
    id cmps2 = [str2 componentsSeparatedByString:@","];        

    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"NOT SELF IN %@", cmps2];
    NSArray *final = [cmps1 filteredArrayUsingPredicate:predicate]; 
    id str = [final componentsJoinedByString:@","];
    NSLog(@"%@", str);

Answer 4

The only solution that I can think of would be this:

NSMutableArray* arr1 = [str1 componentsSeparatedByString:@","] mutableCopy];
NSArray* arr2 = [str2 componentsSeparatedByString:@","];
for (NSString* str in arr2) {
  [arr1 removeObject:str];
}
NSString* newString1 = [arr1 componentsJoinedByString:@","];

Is this what you tried? If "str1" looks something like "1,1,2,2,2", then you might have some more work to do here to get rid of the duplicates. But that's basically it.