You cannot claim a dependent for half a year.
If you were a full time student (which seems to be your case as you were in college for 5 months in 2018) and under 24, your parents can claim you as a dependent for 2018 if you did not provided for more than half of your own support in 2018. Your income for the year does not matter.
And you have to file your taxes as a dependent.
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