I was wondering if there is anyway I can use a PNP transistor on my arduino UNO without any major circuit building ? thanks
Yes.
But as you haven't said what you want to do I can be no more specific than this.
just a simple switch and i dont have any suitable npn transistors
OK, output to a resistor, resistor to the base.
Emitter to the +5V, collector to the load. The other end of the load to ground.
Output HIGH turns the transistor off output LOW turns it on.
thankyou
Think of PNP circuits as the "mirror image" of NPN circuits - so you can take an NPN circuit, reflect it about a horizontal line, replace NPNs with PNPs and you have the complementary circuit (+ve supply is still at the top, -ve at the bottom).
Consider Mike's circuit just described and the standard NPN switching circuit to see this.
In the same way p-channel MOSFETs mirror n-channel MOSFETs...
That is why PNP transistors are sometimes called up side down transistors.
When I first started with electronic there were only PNP transistors and circuited were drawn with the -ve supply at the top.