Comparators - inbuilt sort function

#1

The pdf given on comparators (in inbuilt sort function) doesn’t explain how it works for strings, the code for vector sorting is given under the string heading so can I get some help with that?

#2

Hi Ishita, when we talk of ususal sorting / sorting in ascending order then we must know that value of captial letters is samller than that of lower case i.e.

‘A’ < ‘a’

and the value of the next letter is bigger than previous one i.e.

‘A’ < ‘B’

Now consider a vector arr which contains strings then:

sort(arr.begin(),arr.end()) ;
will sort the array with priorities/rules as above stated.

But if you want to sort them in some special order (decreasing or maybe process them a bit and then decide increase or decrease) then you can use comparator function.

Consider an example. If you are given a vector of strings and you have to sort the strings in increasing order but only on basis of every strings second character then you can do this:

…
…
bool compare( string x, string y ) {
return x[1] < y[1] ;
}
…
…
//somewhere in main or in any other function
sort( arr.begin(), arr.end(), compare ) ;
…
…

Hence you can use comparator for custom sortings.

Hope this helps :slight_smile:

#3

Hey Ishita,
As you are not responding to this thread, I am marking your doubt as Resolved for now. Re-open it if required.

Please mark your doubts as resolved in your course’s “ Ask Doubt ” section, when your doubt is resolved.