Sorting Array based on numbers

Question

I am having an array that contains the values like 2,4,6 etc .Now I want to sort array to find the maximum value,I do not know how to do that. Please Help me. Thanks in advance!!

You need to give more info in your question. What sort of array? A plain C style array? Objective C style array? Is this homework btw? — occulus, Apr 06 '11 at 12:07
@Ramhound Why use quicksort to find the maximum value? It'll take n log n time. Just scanning the array is linear n time. — occulus, Apr 06 '11 at 12:08
NSSortDescriptor *mySorter = [[NSSortDescriptor alloc] initWithKey:@"floatValue" ascending:NO]; [listItems sortUsingDescriptors:[NSArray arrayWithObject:mySorter]]; — vijay adhikari, Apr 06 '11 at 12:35

score 2 · Accepted Answer · edited May 23 '17 at 10:33

2

NSinteger biggest = [[yourArray objectAtIndex:0] integerValue];
for(int i=1; i<[yourArray count]; i++) {
    NSinteger current = [[yourArray objectAtIndex:i] integerValue];
    if(current >= biggest) {
        biggest = current;
    }
}

this will give you the biggest element in the array.

UPDATE

As @occculus suggested you can try fast enumeration. Here is a reference How do I iterate over an NSArray?

FIX

Your code was both wrong (as reported by Kalle) and inefficient (redundant calls of objectAtIndex:). Fixed it, hope you don't mind.
Regexident

edited May 23 '17 at 10:33

Community

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answered Apr 06 '11 at 12:07

visakh7

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Using a fast enumeration would be better. – occulus Apr 06 '11 at 12:09
2

You can't store ints in an array. They are either NSStrings or NSNumbers. In either case you have to add "intValue" to the [yourArray...] calls. – Kalle Apr 06 '11 at 12:27
@Kalle fixed it. Some birdie tells me Jenifer didn't even test it prior to accepting. :P – Regexident Apr 13 '11 at 13:31

score 2 · Answer 2 · answered Apr 06 '11 at 12:37

You can determine the highest value by looking at each value only once.

int highest = INT_MIN;

for (id elem in array)
{
    int current = [elem intValue];
    if (highest < current)
        highest = current;
}

If you want the array to be sorted anyway:

NSArray *sorted = [unsorted sortedArrayUsingSelector:@selector(compare:)];

int highest = [[sorted lastObject] intValue];

Sorting Array based on numbers

2 Answers2