CODEWITHSUNDEEP
cmemorypointers
Irakli
Irakli

Reputation: 941

How to assign pointer address manually in C programming language?

How do you assign a pointer address manually (e.g. to memory address 0x28ff44) in the C programming language?

Upvotes: 69

Views: 161201

Answers (5)

Pawan Kumar
Pawan Kumar

Reputation: 309

In embedded systems while assigning a memory

volatile

must be used, else it is likely that compiler optimization ignores the updated values and uses the old values. Below is a safe method to access the memory

#define ptrVar (*((volatile unsigned long *)0x400073FC)) //ptrVar points to memory location 0x400073FC

ptrVar =10// write 10 at the memory location

Upvotes: 0

Yasir
Yasir

Reputation: 83

let's say you want a pointer to point at the address 0x28ff4402, the usual way is

uint32_t *ptr;
ptr = (uint32_t*) 0x28ff4402 //type-casting the address value to uint32_t pointer
*ptr |= (1<<13) | (1<<10); //access the address how ever you want

So the short way is to use a MACRO,

#define ptr *(uint32_t *) (0x28ff4402)

Upvotes: 2

kamal
kamal

Reputation: 51

int *p=(int *)0x1234 = 10; //0x1234 is the memory address and value 10 is assigned in that address


unsigned int *ptr=(unsigned int *)0x903jf = 20;//0x903j is memory address and value 20 is assigned

Basically in Embedded platform we are using directly addresses instead of names

Upvotes: 5

zsalzbank
zsalzbank

Reputation: 9857

Your code would be like this:

int *p = (int *)0x28ff44;

int needs to be the type of the object that you are referencing or it can be void.

But be careful so that you don't try to access something that doesn't belong to your program.

Upvotes: 12

T.J. Crowder
T.J. Crowder

Reputation: 1074028

Like this:

void * p = (void *)0x28ff44;

Or if you want it as a char *:

char * p = (char *)0x28ff44;

...etc.

If you're pointing to something you really, really aren't meant to change, add a const:

const void * p = (const void *)0x28ff44;
const char * p = (const char *)0x28ff44;

...since I figure this must be some kind of "well-known address" and those are typically (though by no means always) read-only.

Upvotes: 96

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