![]() So, the binary sequence 00001001 is the decimal number 9. The "leftmost" bit in a byte is the biggest.A bit has two values (on or off, 1 or 0).This gives us a common starting point which makes our lives a bit easier: Thankfully, most computers agree on a few basic data formats (this was not always the case). (i.e., we have many ways to say "ten": ten, 10, diez, etc.) Like humans, computers have different ways to store the same abstract concept.Data (bits and bytes, or marks on paper) is meaningless it must be interpreted to create an abstract concept, like a number.Each type of computer is internally consistent (it can read back its own data), but there are no guarantees about how another type of computer will interpret the data it created. Why does this problem happen? Well, there's no rule that all computers must use the same language, just like there's no rule all humans need to. Depending on the assumptions made, the 1's and 0's can mean very different things. Later, they read back the 1's and 0's and try to recreate the abstract concept from the raw data. ![]() They store data, not abstract concepts, and do so using a sequence of 1's and 0's. The point is that a single piece of data (|O) can be interpreted in many ways, and the meaning is unclear until someone clarifies the intent of the author.Ĭomputers face the same problem. Or maybe an abbreviation for Input/Output. They could have been the letters "IO", a moon of Jupiter. If we see a line and a circle (like this: |O) we may interpret it to mean "ten".īut we assumed the marks referred to a number. There is no inherent meaning in these marks. ![]() Data has no inherent meaning and must be interpreted by whoever is reading it.ĭata is like human writing, which is simply marks on paper. Data is a physical concept, a raw sequence of bits and bytes stored on a computer. these representations all point to the same concept of "ten".Ĭontrast this with data. The idea of "ten" doesn't change, no matter what representation you use: ten, 10, diez (Spanish), ju (Japanese), 1010 (binary), X (Roman numeral). The most important concept is to recognize the difference between a number and the data that represents it.Ī number is an abstract concept, such as a count of something. If the header appears backwards, it means data was stored in the other format and needs to be converted. Always include a header that describes the format of the data.Agree to a common format (i.e., all network traffic follows a single format), or.A machine can read its own data just fine - problems happen when one computer stores data and a different type tries to read it.Some write data "left-to-right" and others "right-to-left". Problem: Computers speak different languages, like people.Problems with byte order are frustrating, and I want to spare you the grief I experienced. map(eightBits -> (char)Integer.parseInt(eightBits, 2)) We'll split the string representation of the binary into groups of eight characters, parse them to char variables, and join them into one final String.įor convenience, we'll also ignore empty bytes: Arrays.stream(stringRepresentation.split("(? !eightBits.equals("00000000")) The int variable we created could be easily used as an integer ID, but because we want to have a string ID, we have one more step to do. However, now we're interested in the first 24 bits, and the rest of them are zeros and will be easy to ignore. We still have 32 bits because the int will always have 32 bits. String stringRepresentation = getStringRepresentation(lastThreeBites) ĪssertEquals(stringRepresentation, "00000000010000010100000101000001") ![]() First, we need to get rid of the first eight bits by shifting the variable to the right: int lastThreeBites = intRepresentation > 8 Let's extract the last three bytes of our user account variable and convert them into a string. We can use similar methods to extract multiple bits from an integer. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |