Last month’s Exercise was to write a filter that converts ASCII text into a percent-encoded format. This month, you’re task is to reverse the process: White a filter that converts a percent-encoded string back into the original ASCII.
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I’m frustrated, as are many investors, at the lack of interest generated in “savings” accounts these days. It’s pitiful. The interest formula is based on solid mathematics, which is easy to code in C. Doing so may help you understand the concept of interest and how it works.
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The Change Due Exercise, presented earlier this year, offered a solution that uses the fmod() function. That function is to real numbers as the modulus operator is to integers, though it’s not a straight-across comparison. That’s because floating point numbers can be imprecise.
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The C language offers some delicious predicaments you may not find in other languages. Many of these odd situations involve variables, which are strongly typed in other languages. As a case in point, consider the difference between an empty string and a null string.
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A URL filter isn’t that difficult to code, once you know the rules. I’m sure you can concoct something clever or obfuscated in the C language, but I chose to use a clutch of if/else if/else statements to process input and generate output.
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The C language string-input function was once gets(). That function has become Chernobyl in that it exists but you go there only when you don’t care about your health.
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URL encoding is a method of translating ASCII codes (not just text or URLs) into what’s often referred to as percent encoding. You’ve probably seen this format on your web browser’s address bar or in a search engine’s text. The encoding format is necessary to preserve the original content as plain text.
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In last week’s Lesson, I covered the goto keyword the way most instructors do: I explained that it’s not needed and admonished you not to use it lest you be labeled an complete and utter dork. Still, why would such a superfluous method of program control be included if it’s awkward and unnecessary?
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The only reason anyone learns about the C language keyword goto is because it’s one of the original 32 keywords. The next thing a programmer learns is to avoid it. Peril, pestilence, and pain awaits the fool who uses goto. Yea verily, if a programming Hell exists, goto is the command you use to get there.
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String input is a weird thing when it comes to wide characters, mostly because how the heck do you type wide characters in a terminal window beyond copy-and-paste?
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