Once I saw a case-insensitive switch in C using that pattern of letters: switch (my_char | 0x20) { case 'a': ... break; case 'b': ... break; }
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The Elegance of the ASCII Table
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Re: The Elegance of the ASCII Table
#72Once I saw a case-insensitive switch in C using that pattern of letters: switch (my_char | 0x20) { case 'a': ... break; case 'b': ... break; }
Yes, that’s very intentional and just masking (or setting) the bit is the intended way to do case-insensitive comparison of the letter range in ASCII (eg. stricmp in C), or to transform text to lower or upper case (tolower, toupper).
But what’s more, ever wondered whence the control (Ctrl) key presses like Ctrl-H to backspace, or Ctrl-M for carriage return? Well, inspecting the ASCII chart it becomes evident: the Ctrl key simply masks bit 6 (0x40), turning a letter into its respective control character!
Re: The Elegance of the ASCII Table
#73I wish the author had included the full ascii chart in 4 bits across / 4 bits down. You can mask a single bit to change case and that is super obvious that way. The charts that simply show you the assignments in hex and octal obscure the elegance of the design.
It was at some point looking at a chart like that where it also dawned on me where the control codes like ^D, ^H, ^[ etc came from
I was going to ask you to please explain as I didn't understand, but I am guessing you are talking about the same thing as this comment[1] right? That's super cool
Re: The Elegance of the ASCII Table
#74I think that adopting ASCII as the general purpose text encoding was one of the great mistakes of early computing. It originated as control interface for teletypes and such, and that's arguably where it should have remained. For storing and processing (plain) text ASCII doesn't really fit that well, control characters are a hindrance and the code space would have been useful for additional characters. The ASCII set o…
It's one of the greatest triumphs of early computing. Not only did it harmonize text representation and transmission in a backwards compatible manner; the fact that they deliberately kept it 7 bit for so long also helped for developing a sane set of other language character sets (ISO-8859), and paved the way for a smooth transition to Unicode (UTF-8) - which is now the dominant encoding worldwide.
Re: The Elegance of the ASCII Table
#75The ASCII table is defective; it is missing a dedicated code for newline.
CR and LF aren't dedicated, and have precise cursor movement meanings, rather than being a logical line ender.
There was a proposal in the 80s to reassigning the -otherwise useless- VT (vertical tab) character for the purpose. Unfortunately unfruitful.
Re: The Elegance of the ASCII Table
#76I think that adopting ASCII as the general purpose text encoding was one of the great mistakes of early computing. It originated as control interface for teletypes and such, and that's arguably where it should have remained. For storing and processing (plain) text ASCII doesn't really fit that well, control characters are a hindrance and the code space would have been useful for additional characters. The ASCII set o…
Yeah you were not around when a kb of memory took up half your room. Looking back it doesn't make sense but at the time a byte was what-ever you wanted it to be. Considering number of characters in English language is 26, it is reasonable for a byte to be 5 bits, giving you a total of 32 possible states. Which leaves you with 6 values which could be used as control characters. how-ever lets not forget there are 7,164 other languages of the world, and they all have their own unique way of doing things.
Oh yeah, lets not forget that at the time you had other nationalistic countries/territories/people with their own superior technology all vying for the top position, all well trying to out do each other. Then you also had manipulative monopolies/trade embargo's and wars.
It isn't perfect but people aren't perfect.
Re: The Elegance of the ASCII Table
#77I think that adopting ASCII as the general purpose text encoding was one of the great mistakes of early computing. It originated as control interface for teletypes and such, and that's arguably where it should have remained. For storing and processing (plain) text ASCII doesn't really fit that well, control characters are a hindrance and the code space would have been useful for additional characters. The ASCII set o…
No way!
No amount of extra characters was going to address what Unicode did.
ASCII was not a mistake at all. Adopting it unified what was surely going to be a real mess.
At the time it made sense, and the control functions were needed. Still are.
Re: The Elegance of the ASCII Table
#78> So when you’re reading 7-bit ASCII, if it starts with 00, it’s a non-printing character. Otherwise it’s a printing character. > The first printing character is space; it’s an invisible character, but it’s still one that has meaning to humans, so it’s not a control character (this sounds obvious today, but it was actually the source of some semantic argument when the ASCII standard was first being discussed). Hmm..…
While DEL didn't stamp a black square on typewriters, it sometimes did so (or something similar, like diagonal stripes) in various digital character sets. ISO 2047[0] established the graphical representations for the control characters of the 7-bit coded character set in 1975, maily for debugging reasons. This graphical representation for DEL was used by Apple IIGS, TRS-80 and even Amiga!
Re: The Elegance of the ASCII Table
#79I think that adopting ASCII as the general purpose text encoding was one of the great mistakes of early computing. It originated as control interface for teletypes and such, and that's arguably where it should have remained. For storing and processing (plain) text ASCII doesn't really fit that well, control characters are a hindrance and the code space would have been useful for additional characters. The ASCII set o…
It's one of the greatest triumphs of early computing. Not only did it harmonize text representation and transmission in a backwards compatible manner; the fact that they deliberately kept it 7 bit for so long also helped for developing a sane set of other language character sets (ISO-8859), and paved the way for a smooth transition to Unicode (UTF-8) - which is now the dominant encoding worldwide.
Yes, seconded easily
Re: The Elegance of the ASCII Table
#80Earlier quoted context omitted.
The record separator isn't on people's keyboards, so it's less likely to show up where it's not expected. Also it's less likely to legitimately occur in something like a name, so there are many users of CSVs who can say they will never need to consider data containing a record separator, and they will be right more often than those who never consider data containing a comma. Of course, the fact that record separators…
In the DOS days, you could "type" control characters by pressing Ctrl and the corresponding letter key, Ctrl+M is Carriage Return, Ctrl+H is Backspace, Ctrl+Z is End Of File, etc. It was probably possible to type an RS with Ctrl+Shift+. and the others with similar combos.
I think it's worth mentioning that Ctrl-A is ascii 1, Ctrl-B ascii 2, etc, as it is in Unix today.