A bit string is a bunch of bits, like 01010011. string A string is a bunch of items strung together.
#Character encoding list code
code page A "page" of codes that map a character to a number or bit sequence. "The ASCII encoding encompasses a character set of 128 characters." Essentially synonymous to "encoding". Other terms which deserve clarification in this context: character set, charset The set of characters that can be encoded. An encoding is the set of rules with which to convert something from one representation to another. To encode means to use something to represent something else. To decode a string of bits into human readable characters, follow the table from left to right, substituting bits for letters.Ī system of words, letters, figures, or other symbols substituted for other words, letters, etc. To encode something in ASCII, follow the table from right to left, substituting letters for bits. 1Īnd there you have it, the way to represent human-readable text using only 1s and 0s. In total there are 128 characters defined in the ASCII encoding, which is a nice round number (for people dealing with computers), since it uses all possible combinations of 7 bits ( 0000000, 0000001, 0000010 through 1111111). A number of values are only useful to a computer, like codes to signify the start or end of a text. These are not printable per se, but still visible in some form and useful to humans directly. It also includes 33 values for things like space, line feed, tab, backspace and so on. There are 95 human readable characters specified in the ASCII table, including the letters A through Z both in upper and lower case, the numbers 0 through 9, a handful of punctuation marks and characters like the dollar symbol, the ampersand and a few others. Here's a short excerpt of that table: bits The ASCII encoding specifies a table translating bytes into human readable letters. A string of 1s and 0s is broken down into parts of eight bit each (a byte for short). The above encoding scheme happens to be ASCII. If you can keep this in your head for 26 letters or are really fast with looking stuff up in a table, you could read bits like a book. A certain sequence of bits stands for a letter and a letter stands for a certain sequence of bits. We need to convert a sequence of bits into something like letters, numbers and pictures using an encoding scheme, or encoding for short. To use bits to represent anything at all besides bits, we need rules. For humans, this is usually represented using 1 and 0 and I'll stick with this convention throughout this article. Since a computer works with electricity, an "actual" bit is a blip of electricity that either is or isn't there. A bit can only have two values: yes or no, true or false, 1 or 0 or whatever else you want to call these two values. The only thing it can store and work with are bits. Getting the basics straightĮverybody is aware of this at some level, but somehow this knowledge seems to suddenly disappear in a discussion about text, so let's get it out first: A computer cannot store "letters", "numbers", "pictures" or anything else. This article is aimed at developers (with a focus on PHP), but any computer user should be able to benefit from it. I hope this article can shed some more light on what exactly an encoding is and just why all your text screws up when you least need it. I hesitate to refer people to it who have trouble understanding encoding problems though since, while entertaining, it is pretty light on actual technical details.
#Character encoding list software
An article by Joel Spolsky entitled The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (No Excuses!) is a nice introduction to the topic and I greatly enjoy reading it every once in a while. This article is about encodings and character sets.
And the good news first: while the topic can get messy and confusing, the basic idea is really, really simple. You don't need to understand every last detail, but you must at least know what this whole "encoding" thing is about. Yes, even if you are just sending emails. If you are dealing with text in a computer, you need to know about encodings. What every programmer absolutely, positively needs to know about encodings and character sets to work with text What Every Programmer Absolutely, Positively Needs to Know About Encodings and Character Sets to Work With Text
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