My 99 honda wont start?

I was noticing my 99 honda prelude wasnt starting as strong as normal the last couple days. thought it was either the battery or the starter. Finally today to try and determine the problem I hooked up jumper cables and started it and stopped it 3 times, and on the 3rd time it wouldnt start. is this for sure the starter? I'm about to go buy one but wanted to be 100% sure that I wasnt buying the wrong part