Just to add..If you look at the sticker on the PSU, it will tell you the AC Input Voltage range is from 100V to 240V and it will auto-detect the input voltage and auto-switch to using the supplied voltage as MattM said..Some PSUs still do come with a voltage selector switch though, but most all don't anymore.

That goes for many other products too, such as hair dryers, TVs, electric razors, phone chargers, laptops..They'll usually always say somewhere what the input voltage can be and many of them will auto-detect and auto-switch also so they can be used internationally..So keep that in mind in case you have other electric things you might be wondering about.

You can use an adapter in a pinch, but buying another cable with the correct wall socket end is the best way to go, they're not expensive and can be found just about anywhere..The end that goes into PSU is an industry-standard C13. 

rjohnson11
PSU manufacturers found out long ago that it is far cheaper to make an auto-detecting PSU rather than build separate PSUs for each world region.

We still have a few very low wattage power supplies with the switch but yes, the auto-switching has taken over for the most part which is good as I have seen too many people over the years flip the switch to the wrong side and caused issues. The only difference between our power supplies in the regions is the power cords in the boxes which is why some have part number suffixes with a 2 or 3. It just means it has a UK or EU power cord in the box.