cplusplus:pointers_3_slides
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cplusplus:pointers_3_slides [2019/03/31 21:26] – mithat | cplusplus:pointers_3_slides [2021/10/24 02:46] (current) – [Pointer arithmetic: addition] mithat | ||
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Pointers, arrays, arithmetic.\\ | Pointers, arrays, arithmetic.\\ | ||
Mithat Konar\\ | Mithat Konar\\ | ||
- | March 31, 2019 | + | October 23, 2021 |
===== Pointers and arrays ===== | ===== Pointers and arrays ===== | ||
* Arrays and pointers are closely related. | * Arrays and pointers are closely related. | ||
- | * An array name is like a constant | + | * Array names are like a constant |
* the block of memory where an array name points cannot be changed, | * the block of memory where an array name points cannot be changed, | ||
* what is stored there can change. | * what is stored there can change. | ||
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===== Pointer arithmetic ===== | ===== Pointer arithmetic ===== | ||
- | | + | * Pointer arithmetic works differently |
- | | + | |
* '' | * '' | ||
* E.g., adding 1 to a pointer makes it point to the next block of memory corresponding to the size of the underlying type. | * E.g., adding 1 to a pointer makes it point to the next block of memory corresponding to the size of the underlying type. | ||
+ | |||
<file cpp pointer-math.cpp> | <file cpp pointer-math.cpp> | ||
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} | } | ||
</ | </ | ||
+ | |||
+ | ===== Pointer arithmetic: pointer difference ===== | ||
Subtracting one pointer from another returns the number of elements between two addresses: | Subtracting one pointer from another returns the number of elements between two addresses: | ||
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</ | </ | ||
- | ==== Walking down an array ==== | + | ===== Walking down an array ===== |
A common technique used to visit every element in an array is to //walk down an array// with a pointer: | A common technique used to visit every element in an array is to //walk down an array// with a pointer: | ||
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</ | </ | ||
- | This is especially | + | Especially |
<file cpp walk-null-terminated.cpp> | <file cpp walk-null-terminated.cpp> | ||
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===== Summary ===== | ===== Summary ===== | ||
- | The examples below assume: | + | The following |
<code cpp> | <code cpp> | ||
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</ | </ | ||
- | ==== Array access techniques ==== | + | ===== Array access techniques |
^ Access technique | ^ Access technique | ||
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- | ==== Array arithmetic ==== | + | ===== Array arithmetic |
^ Operation | ^ Operation | ||
- | |Increment | + | |< |
- | |Decrement | + | |< |
- | |Arithmetic | + | |< |
- | |Compound assignment | + | |< |
valptr += 2; // points at 11</ | valptr += 2; // points at 11</ | ||
- | |Pointer subtraction | + | |< |
cplusplus/pointers_3_slides.1554067586.txt.gz · Last modified: 2019/03/31 21:26 by mithat