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Status: Tags: Links: C MOC

Pointers and References

• C Constant Pointers
• Void Pointers

Pointers

• Dereferencing
  • useful when you only have the address in memory and you want to read or write the value in the address.
• 8 bytes
• Hold the location of variables
• Can change parameters of functions
• Used to modify variables sent to a function by getting adress as parameter
  • void foo(int* a) as parameter, call using foo(&a)
• * plays 2 roles
  • When we declare a variable which is a pointer.
  • When we want the value in the address. (Read or write)

Uses

• Allow us the modify parameters in a function
• Allows us to pass large objects to a function with a single pointer.
• Optimization: Avoids duplicating data
• Arrays are implemented using pointers in C
  • So are strings

Syntax

& to get adress of a value * access value at the adress

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int* px = &x; //create pointer var to adr of x

*px = 7; //value at var px is changed to 7

int x = 5; int* px = &x; // pointer to location x
//int* is a type 
printf("The address in memory of %d is %p|", x, px); 
>> The address in memory of 5 is 0x9a58af3c4 
// %p is a pointer and address is usually in hexadecimal

Questions

? a = 7, b = 1, c = 2

Backlinks

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Created:: 2021-09-13 14:35