cplusplus:pointers_2_slides
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cplusplus:pointers_2_slides [2019/03/28 17:38] – [Pointer to constant data] mithat | cplusplus:pointers_2_slides [2021/10/19 19:43] – [Constant pointers] mithat | ||
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~~NOTOC~~ | ~~NOTOC~~ | ||
- | ====== Pointers 2 ====== | + | ====== Pointers 2 slides |
Pointers and comparisons, | Pointers and comparisons, | ||
Deitel, Harvey M., and Paul J. Deitel. " | Deitel, Harvey M., and Paul J. Deitel. " | ||
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* Arguments can be anything that can be assigned to a pointer (i.e., addresses or pointers). | * Arguments can be anything that can be assigned to a pointer (i.e., addresses or pointers). | ||
+ | ===== Example ===== | ||
<file cpp function-with-pointer.cpp> | <file cpp function-with-pointer.cpp> | ||
/** Demonstrates how to pass pointers to functions. */ | /** Demonstrates how to pass pointers to functions. */ | ||
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* Pointers can be used to implement //pass by reference// in functions. | * Pointers can be used to implement //pass by reference// in functions. | ||
* The '' | * The '' | ||
- | | + | * Strictly speaking, the passing mechanism is //call by value//. But functionality is pass by reference. |
- | | + | * Syntax |
- | * The syntax | + | |
+ | ===== Example ===== | ||
<file cpp cube-by-reference.cpp> | <file cpp cube-by-reference.cpp> | ||
/** Cube a variable using pass by reference with a pointer. */ | /** Cube a variable using pass by reference with a pointer. */ | ||
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void cubeByReference(int *nPtr) | void cubeByReference(int *nPtr) | ||
{ | { | ||
+ | // *nptr'' | ||
*nPtr = (*nPtr) * (*nPtr) * (*nPtr); // parenthesis for readability | *nPtr = (*nPtr) * (*nPtr) * (*nPtr); // parenthesis for readability | ||
} | } | ||
</ | </ | ||
- | --------------------------------------------------------------------------------------------------------------- | + | ===== The const qualifier ===== |
- | ===== The const qualifier and pointers ===== | + | |
- | + | ||
- | | + | |
* '' | * '' | ||
* '' | * '' | ||
- | | + | |
+ | ===== The const qualifier ===== | ||
+ | | ||
* What is constant? The pointer value or the value of the thing pointed to? | * What is constant? The pointer value or the value of the thing pointed to? | ||
* Answer is //either or both//. | * Answer is //either or both//. | ||
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* A **constant pointer** is a pointer whose value cannot change. | * A **constant pointer** is a pointer whose value cannot change. | ||
- | * Constant pointers store a memory location that cannot be changed. | + | * Constant pointers |
* Must be initialized when declared. | * Must be initialized when declared. | ||
- | * Use the '' | + | * '' |
<code c++> | <code c++> | ||
- | int * const myPtr = & | + | int *const myPtr = & |
+ | // myPtr will always point to x | ||
</ | </ | ||
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{ | { | ||
int x = 2, y = 5; | int x = 2, y = 5; | ||
- | int * const myPtr = & | + | int *const myPtr = & |
// The data pointed to by myPtr can be | // The data pointed to by myPtr can be | ||
// modified through myPtr, but myPtr must | // modified through myPtr, but myPtr must | ||
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<code c++> | <code c++> | ||
- | /* const modifies myPtr'' | + | /* const modifies myPtr, meaning the value of myPtr is constant. */ |
int *const myPtr = &x; | int *const myPtr = &x; | ||
</ | </ | ||
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<code c++> | <code c++> | ||
- | /* const'' | + | /* const modifies int, meaning the value of the int is constant. */ |
const int *myPtr = &x; | const int *myPtr = &x; | ||
</ | </ | ||
cplusplus/pointers_2_slides.txt · Last modified: 2021/10/19 19:46 by mithat