
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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Ctype Functions: isascii() and iscntrl()

I almost believe these two functions to be useless, but they do play an important role in the ctype pantheon: isascii() determines whether an integer value is an ASCII character, and iscntrl() lets the program know further whether an integer value is also an ASCII control code. This pair adds to my continuing exploration of the ctype functions.
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That Series That Lacks a Name but Equals 5e – Solution
Once again, I dive into the murky waters of mathematics for this month’s Exercise. The challenge is to code the Series That Has No Name (STHNN), which converges on the value 5e.
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Ctype Functions: isblank() and isspace()

You can draw a blank and you can get spaced out, so there’s a difference in the English language between the words “space” and “blank.” This difference doesn’t explain how the ctype functions isblank() and isspace() work. In this Lesson, I cover these two functions and their differences, as I continue my exploration of the ctype functions.
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That Series That Has No Name but Equals 5e
Difficulty: ★ ★ ☆ ☆
I’d like to know when mathematicians arrive at their “a-hah!” moments. Do they just have an equation pop into their head and mutter, “Golly, I wonder what that means?” Or do they wake up screaming in the middle of the night? Personally, I can well connect with the latter.
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Ctype Functions: isgraph() and isprint()

Two very similar ctype functions are isgraph() and isprint(). Only one character separates the two functions. And the isgraph() function has nothing to do with graphics. These are the topics for this week’s Lesson as I continue my exploration of the ctype functions.
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Ctype Functions: isalnum(), isalpha() and isdigit()

The ctype functions isalnum(), isalpha(), and isdigit() examine the alphanumeric ASCII characters. Each of these functions are related, so I cover them together in this post that continues my exploration of the ctype functions.
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Ctype Functions: isupper() and islower()

I wouldn’t say that the isupper() and islower() functions are the opposite of the toupper() and tolower() functions, though they do play well together. This week I continue my exploration of the ctype functions.
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Ctype Functions: toupper() and tolower()

The easiest way to mess with characters in C is to employ the ctype functions. I name this category of library functions after the ctype.h header file that defines them. Some are true functions, some are macros. Each function can be replicated with standard C code, though it’s quicker to use an established function than to code your own. But that’s not the point of learning to program!
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Pointers to Multi-Dimension Arrays – Solution
The challenge for this month’s Exercise is to use pointers to work through a multi-dimensional array. As I mentioned in the exercise post, multi-dimensional arrays are all stored as a single-dimension where the compiler calculates offsets for rows and columns (and more) for you.
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