cplusplus:pointers_3_slides
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| cplusplus:pointers_3_slides [2019/03/31 21:17] – mithat | cplusplus:pointers_3_slides [2021/10/24 02:45] – [Pointer arithmetic: subtraction] 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. | ||
| Line 51: | Line 51: | ||
| ===== Pointer arithmetic ===== | ===== Pointer arithmetic ===== | ||
| - | C++ lets you perform arithmetic on pointer variables; however, // | + | * Pointer |
| + | * '' | ||
| + | * E.g., adding 1 to a pointer makes it point to the next block of memory corresponding to the size of the underlying type. | ||
| + | |||
| + | ===== Pointer arithmetic: addition ===== | ||
| + | * Adding 1 to a pointer makes it point to the next block of memory corresponding to the size of the underlying type. | ||
| - | In other words, adding 1 to a pointer makes it point to the next block of memory corresponding to the size of the underlying type; subtracting 1 from a pointer makes it point to the previous block of memory corresponding to the size of the underlying type. This is really only meaningful when performed on an array. | ||
| <file cpp pointer-math.cpp> | <file cpp pointer-math.cpp> | ||
| Line 77: | Line 81: | ||
| } | } | ||
| </ | </ | ||
| + | |||
| + | ===== 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: | ||
| Line 97: | Line 103: | ||
| </ | </ | ||
| - | ==== 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: | ||
| Line 121: | Line 127: | ||
| </ | </ | ||
| - | This is especially | + | Especially |
| <file cpp walk-null-terminated.cpp> | <file cpp walk-null-terminated.cpp> | ||
| Line 145: | Line 151: | ||
| ===== Summary ===== | ===== Summary ===== | ||
| - | The examples below assume: | + | The following |
| <code cpp> | <code cpp> | ||
| Line 152: | Line 158: | ||
| </ | </ | ||
| - | ==== Array access techniques ==== | + | ===== Array access techniques |
| ^ Access technique | ^ Access technique | ||
| Line 161: | Line 167: | ||
| - | ==== 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.txt · Last modified: 2021/10/24 02:46 by mithat