Difficulty: ★ ★ ★ ☆
The classic paradigm for swapping values between two variables involves using a third variable. But is the third variable even necessary?
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Swapping Variables
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Author Archives: dgookin
The Improved nano_delay() Function (I Hope)
Last week’s Lesson explored using the clock_gettime() function to pause program execution for a given number of nanoseconds. The code, however, contains a flaw that may render an inaccurate result.
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Your Own Time Delay Function
I’ve written about my own delay() function, which uses processor clock ticks to calculate a time delay in milliseconds. Thanks to the clock_gettime() function, I can write a new time-delay function that operates from nanoseconds — or close to it. I hope.
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Programming with Nanoseconds
From last week’s Lesson, the clock_gettime() function returns values in both time_t (Unix Epoch) seconds as well as nanoseconds. This rich variety makes the function quite useful for coding time-critical details where values less than a second are desired.
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Yesterday – Solution
The challenge for this month’s Exercise is to output yesterday’s date: the day of the week, day of the month, month, and year. It’s not as complex as it could be, though keep in mind that any code that outputs the proper result is valid.
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Checking the Time
I tend to keep the lessons on this blog specific to the standard C library, C99 release. Yet every so often a newer function draws my attention, which may not be standard but can still be useful. Case in point is the clock_gettime() function, which subscriber M.Stumpfl mentioned in a previous post.
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Yesterday
Difficulty: ★ ★ ☆ ☆
The time.h header defines a handful of functions useful for discovering and manipulating today’s date. Especially the localtime() function, which translates a time_t (Unix Epoch) value into date fields for output or manipulation. It’s a wonderful tool, but what does it tell you about yesterday?
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What the Heck is That Thing?
I just moved to a new computer. The process involved taking all my personal programs and re-compiling them for the new system. It took a while, but fortunately everything works with my various programs doing their necessary jobs. That is, unless I see a weirdo error upon compiling one of those golden oldies. On such error I saw made me wonder what they heck I was doing in my code.
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The Final Output to HTML Code
The final update to the sconvert function includes translating characters &, <, and > for proper HTML output. With this update to the code from last week’s Lesson, the conversion filter is complete and can be used to translate C program text output into HTML code that I can easily post on the web.
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Properly Padding Spaces and Tab Widths
The task for last week’s Lesson was to convert tabs as well as spaces. The problem is that tab stops aren’t considered: On the terminal, a tab character generates a variable number of spaces based on where the next tab stop position is located. It isn’t a fixed value.
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