The standard library functions atoi() and atof() work well to translate text (ASCII) input into values, an int or float, respectively. When your code must know whether a string is really a value, more processing is required.
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My philosophy is to treat the input as a string until I can confirm that it’s not. The question then rises as to how strings can best translate into a value.
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In Part II of this series, I showed code that let you pass a pointer’s address to a function. Within that function, the address can be manipulated and value at that address displayed. Can the same thing be done with a two-dimensional array, which is loosely related to a ** pointer?
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Those programmers I wrote about in last week’s Lesson, the ones who avoid the ** pointer notation, usually do so by using a two-dimensional array instead of the ** pointer thing. It’s a quick substitute, but it’s not exactly the same thing.
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I know C programmers who make it their goal to avoid pointers — even where necessary. It’s possible to do so, and many have cheat sheets to help them. Then comes the ** pointer monster, which can be avoided altogether . . . until you need to manipulate a pointer variable’s own address within a function. Then you’re cursed.
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When a function must manipulate a pointer’s address, the argument passed is a pointer-pointer, not a pointer. Confused? Oh, I’m just getting started . . .
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It’s common to pass a pointer to a function. Within the function, you can manipulate the data the pointer references without having to return that data from the function. This aspect of a pointer is what makes C a powerful — and scary — programming language. But what about when you need to manipulate the pointer’s address in the function?
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Logic can be frustrating, especially for non-Vulcans. The computer is kind of a Vulcan, so logic comes naturally to the machine. Programming languages are packed with logical expressions. A programmer’s duty is to convert human thoughts into the raw, powerful logic the computer understands — and end up with the desired result.
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In last week’s Lesson, I showed a program that translates a string of hex values into ASCII text. This code was to sate the nerd in me so that when another nerd writes 48 65 6c 6c 6f 2c 20 66 65 6c 6c 6f 77 20 6e 65 72 64 21, I can respond accordingly. But to respond in hex, a second program is required, one that translates ASCII text into a string of hex values.
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Do you speak hex? As a programmer, do you look at 0xF and see 1111 in binary? Do you see 15 decimal? What about the ASCII code? Do you know the letter for code 0x41? Are you that good?
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