IFD:GrundlagenElektronik2011/BasicsCourse: Difference between revisions

So this seems all logical - however there's a small trap in using this representation. If all bits are zero everything is clear - the number 0000 0000 means positive and the number is zero. But 1000 0000 means negative - and also zero. This may cause problems (and in Fact there are problems likely to be related on this: The lidl cash system crashed when you bought items for an amount and then gave empty bottles so the resulting price should be zero. ) and so there are several definitions to have only one zero. Unfortunately this looks not very intuitive at first:

You don't have to remember this when programming simple things - however this may become important if you use bitwise operations. Important for now is only that the upper and lower limit of a signed int in Arduino differ by 1 bit.

Since you want to store several numbers you have to find a way to store keep them remembered. A common way to accomplish that is giving names to such a variable:

now Arduino knows that you are going to use 2 integers. Their content is now the value 0 - that's for convenience.

after declaring the variables you can store something in them:

stores 20 and 30 in variables called myNumber and anotherNumber.

Every time you need one of those numbers you can use myNumber and anotherNumber. Their values don't change until you order them to do so, for example by writing:

now the 20 is forgotten and the value of myNumber is 25.