CODEWITHSUNDEEP
objective-calgorithm
user1808433
user1808433

Reputation: 3405

How to check the greater value in Objective-C?

I am creating a graph. I get 5 values at run time so how should I know which is greater so that I may set max limit?

I have following 5 varibale of values;

int value3=(int)roundf(appDelegate.itemOneValue);
int value4=(int)roundf(appDelegate.itemTwoValue);

int value5=(int)roundf(appDelegate.itemThreeValue);

int value6=(int)roundf(appDelegate.itemFourValue);

int value7=(int)roundf(appDelegate.itemFiveValue);

How to check which of the above variables has the larger value?

Upvotes: 0

Views: 143

Answers (2)

elp
elp

Reputation: 8131

You can read a great article on wikipedia: http://en.wikipedia.org/wiki/Selection_algorithm

Here the pseudo-code to get min/max from an array:

 function select(list[1..n], k)
     for i from 1 to k
         minIndex = i
         minValue = list[i]
         for j from i+1 to n
             if list[j] < minValue
                 minIndex = j
                 minValue = list[j]
         swap list[i] and list[minIndex]
     return list[k]

In objc, the pseudo code became something like this:

  int value3=(int)roundf(appDelegate.itemOneValue);
  int value4=(int)roundf(appDelegate.itemTwoValue);
  int value5=(int)roundf(appDelegate.itemThreeValue);
  int value6=(int)roundf(appDelegate.itemFourValue);
  int value7=(int)roundf(appDelegate.itemFiveValue);

  NSArray *values = @[[NSNumber numberWithInt:value3],
                      [NSNumber numberWithInt:value4],
                      [NSNumber numberWithInt:value5],
                      [NSNumber numberWithInt:value6],
                      [NSNumber numberWithInt:value7]];
  NSNumber min=0;
  NSNumber max=0;
  for ( int i=0; i<[values count]; i++ ) {
    min = [values objectAtIndex:i];
    //etc...
    for (int j=0; j<i+1; j++ ) {
      if ( [values[j] > min] ) {
        // etc..
      }
    }
  }

hope this helps.

Upvotes: 0

Hermann Klecker
Hermann Klecker

Reputation: 14068

NSArray *allValues = @[[NSNumber numberWithInt:(int)roundf(appDelegate.itemOneValue)], 
    [NSNumber numberWithInt:(int)roundf(appDelegate.itemTwoValue)], 
    [NSNumber numberWithInt:(int)roundf(appDelegate.itemThreeValue)], 
    [NSNumber numberWithInt:(int)roundf(appDelegate.itemFourValue)],
    [NSNumber numberWithInt:(int)roundf(appDelegate.itemFiveValue)]];

int max = [[allValues valueForKeyPath:@"@max.intValue"] intValue];

or

NSNumber * max = [allValues valueForKeyPath:@"@max.intValue"];

An alternative that is less flexible but may be easier to understand: 

int max = (value2 < value1) value2 : value1;
max = (value3 < max) value3 : max;
max = (value4 < max) value4 : max;
max = (value5 < max) value5 : max;
max = (value6 < max) value6 : max;
max = (value7 < max) value7 : max; 
// now max contains the highest of all values.

Upvotes: 2

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