What is the legal status of a child born to a dating couple .Is the child treated as illegitimate child .?

dating is no official status, dating doesn't even mean that you have sex, it is possible to date a couple of different people at the time.

If you date and have sex and a child results, the child is born outside a marriage and would in former times considered illegitimate.

Of course the child is illegitimate. But that does not mean a whole lot these days. Both parents are required to provide for all their child's needs.

To protect the child, the unmarried parents need to get a court order of their agreement on custody, child support, etc. Actually, it's marriage which protects a child. Without marriage, you two need to arrange for your child's care, including what happens if one of you dies or becomes incapacitated, etc. If you do not come to some agreement, put it in writing, and get court authority, your child is in danger!

Legal status is illegitimate if parents are not married.

There is no 'different' treatment of children born in marriage or not in marriage in civilised societies, however yes they are illegitimate

You'll need to include what sort of fucked up country you come from. The civilized world no longer makes such distinctions and does not distinguish children as illegal.

you don't give a country

the status of the parents

if fact nothing