inehar :
Hello,
the pc says input 1.5 A and output 3.42 A which is correct,in all other appliance it is given straightforward either in amps or watts why not in the
computer.
What's not straightforward about what you just wrote? The power supply takes in 1.5A AC current and converts it to 3.42A DC current. If you're replacing the power supply, you want one that outputs the same voltage as the one you have at an equal or higher current.
If you want to know the wattage, you can do some simple math.
Power=Voltage*Current
Take the output potential (voltage) and multiply it by your 3.42 A current and you get the power (in watts) of your power supply. Your voltage is probably somewhere around 19 V, since most notebooks consume ~65 watts at full load. It might not be, though.