Details about a pointer can easily be obtained and output: it’s name, address, and contents. Obtaining the size of the buffer it references, however, is a different animal.
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Clearing the pointer hurdle is a major leap to learning the C programming language. Using the malloc() function to allocate storage is central to grasping this concept. Then along comes the realloc() function, and minds are blown.
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The rules for naming variables, or identifiers, in C are simple: The names must start with a letter and contain letters and numbers. The _ (underscore) counts as a letter. Upper- and lowercase letters are considered differently. And only the first 31 characters are significant, though some platforms may extend this length.
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Sometimes I turn off my programmer brain and look at code to admire it in an innocent way. At first glance a C program source code file looks poetic, using the same patterns and flow. Code is also cryptic, which inspires many programmers to try to invent a new way to do something in a charming and confusing manner. One of my attempts was to rationalize this expression: ++a++
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One of the burdens of being a programmer is that few people are witness to your brilliance. You can write the keenest code since the Countess of Lovelace and it’s likely no one will ever appreciate your genius. But don’t let this limitation stop you!
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Nothing paralyzes a C programmer like double-asterisk notation. What does it mean? Can you use it? How is it passed to a function and then referenced? I, too, fall victim to this confusion. So a good explanation is in order.
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C is stream oriented, but in a terminal window you can use ANSI commands to provide more control. These commands can change text color as well as manipulate the cursor’s location, as covered in this month’s Exercise solution. The manipulation isn’t over yet!
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One of my first programming obsessions was online communications. I wrote several modem programs for the TRS-80 (in Z80 Assembly) and then moved to the IBM PC/MS-DOS where I coded communications programs in both Assembly and C. I learned a few things.
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The final (and merciful) update to my Grid of Random Stars program involves two major changes. First, because I call the update_grid() function only once, it can be incorporated into the main() function, no program. Second, I remove pointer notation.
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The program may output what I want, but the code isn’t done yet. Continuing from last week’s Lesson, I’d like the program to output a single grid showing a summary of all the rectangles found. This update requires more changes to the existing code.
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