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Pointers
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Using the reference operator & and the dereference operator *, we can create and work with pointers.
A pointer is a data type, just like int, char, or double.
The pointer is designed to store an address, which you can obtain using the & operator.
To declare a pointer, prepend it with the * character.
int* intPointer; // pointer to an int variable
double* doublePointer; // pointer to a double variable
char* charPointer; // pointer to a char variable
In essence, a pointer is a variable that holds the address of another object.
int x = 100; // variable
int* pX; // pointer to an int variable
pX = &x; // pX now points to x
Note
Typically, pointers are named by prefixing the letter
pto the name of the object they're pointing to.
When you dereference a pointer, you access the value of the variable it points to.
Main.c
1234567891011121314#include <stdio.h> int main() { int x = 22543; // variable int* pX = &x; // `pX` is pointer to `x` printf("The value of `pX` is %p\n", pX); // value of pointer `pX` printf("The value of `x` by pointer `pX` is %d\n", *pX); // pointer dereference return 0; }
Note
*(&variable) == *pVariable
If you attempt to dereference a null pointer, the compiler will raise an error:
Example provided to showcase the mistake
Main.c
12345678910#include <stdio.h> int main() { int* pX; printf("x = %p", pX); return 0; }
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Determine the size of int and double pointers.
Soluzione
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