Srinivasa Ramanujan was a mathematician of the genius variety in that he did amazing things in his short lifetime. The man was insanely brilliant. In fact, he struggled to get other mathematicians to understand his work because it was so unfamiliar. Anyway, he concocted the thing shown in Figure 1, which is one of many Ramanujan Nested Radicals:
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The for keyword opens the door to looping in C, as well as in other programming languages. When teaching this concept, I keep the for loop format simple. After all there’s a lot of cryptic stuff between those parenthesis. And — brace yourself — there’s room for a lot of other stuff as well.
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Anyone who’s programmed in C for a while has worked with other libraries. In Linux, it’s common to link in the math library, libm.a. Other libraries are available to expand what the C language can do. I have books available on Ncurses, curl, XML and JSON, each of which has a library that makes it easy to use these powerful utilities. But what about making your own library?
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As I plow the digital seas, I often come across a piece of programming flotsam worthy of investigation. Most of it is obfuscated C, which is delightful. The obfuscated code that outputs something wonderful is most entertaining. But every so often I stumble upon something perplexing like the following code:
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When I first learned Assembly Language, I had a fear of blowing up the stack. Remember, back in the 8-bit microcomputer era that memory space was tight, maybe only part of 64K. A stack would have 1K of storage, if that. I think the stack size on my TRS-80 was 256 bytes. (An address was only two bytes wide.) This limitation meant that pushing too much data on the stack would blow up the computer.
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As a wrap-up for my ctype questions, this month’s Exercise is to write a ctype function that converts lowercase Greek letters to uppercase and vice-versa. This challenge isn’t a steep hill to climb, once you know the pattern of Unicode Greek letter values, and ignore the required accent and breathing marks that frequently adorn various letters.
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Today is Independence Day in the USA. Two hundred and fifty years ago, this nation’s founding fathers signed the Declaration of Independence. While I’ve had posts dated July 4 previously on this blog, today is a special anniversary. It necessitates a specific C language program.
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My recent ctype series got me thinking: What about coding a specific function that works with a non-Latin alphabet? The first alphabet I thought of was Greek. Why not check out the Unicode values of Greek and see whether you can code a few ctype functions that deal with this character set?
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The ctype isxdigit() function returns TRUE for any digit you find in a hexadecimal number. I suppose this function has a role to play, most likely in detecting hexadecimal characters in a string. Regardless, this post wraps up my exploration of the ctype functions.
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For the ctype ispunct() function, the goal is to understand that “punct” is short for punctuation and not puncture. To put this function to use you need to know what the library considers to be an ASCII punctuation character. It’s yet another step forward in my ongoing exploration of the ctype functions.
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