Regarding -1 done in lb

#1

why -1 is done in the lb bound when we have changed the compare function and what is this compare function actually doing

#2

@sharad1103 the compare functions gives you the first value that is GREATER than the key, that’s why you have to do -1 in the iterator.

#3

without compare function also the lower bound gives the index of greater or equal number?

#4

use of compare is to give only greater number not equal??

1 Like
#5

Yes you got that right

#6

than why are we doing a<=b in compare it would return the last number that is less than or equal to key

#7

then why are we doing a<=b in compare it would return the last number that is less than or equal to key how will it return the greater one?

#8

what is the actual compare code of default lower_bound function?

#9

@sharad1103 that compare function ensures that equal values are passed as well and only a > b returns false, so that the first element to fail the condition a <= b is returned. It is basically converted to the upper_bound function.

#10

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