assigning a memory address to a pointer

This is a discussion on assigning a memory address to a pointer within the C Programming forums, part of the General Programming Boards category; Normally an address is assigned to a pointer this way: Code: int X, *ptr=&X; How can I assign the address ...

  1. #1
    spurious conceit MK27's Avatar
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    assigning a memory address to a pointer

    Normally an address is assigned to a pointer this way:
    Code:
    int X, *ptr=&X;
    How can I assign the address from a string literal, Eg.

    Code:
    #define addr "0xbfe146bc"
    *ptr=addr;  //obviously not
    Such that this will now be the actual address of the pointer and usuable that way normally (if you need to know why, see
    accessing memory used by another program
    C programming resources:
    GNU C Function and Macro Index -- glibc reference manual
    The C Book -- nice online learner guide
    Current ISO draft standard
    CCAN -- new CPAN like open source library repository
    3 (different) GNU debugger tutorials: #1 -- #2 -- #3
    cpwiki -- our wiki on sourceforge

  2. #2
    CSharpener vart's Avatar
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    convert it to unsigned long using strtoul
    then, cast to pointer of the appropriate type
    The first 90% of a project takes 90% of the time,
    the last 10% takes the other 90% of the time.

  3. #3
    spurious conceit MK27's Avatar
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    Quote Originally Posted by vart View Post
    convert it to unsigned long using strtoul
    then, cast to pointer of the appropriate type
    I presume that's what you were trying to do with your example in the other thread, but it doesn't work!
    C programming resources:
    GNU C Function and Macro Index -- glibc reference manual
    The C Book -- nice online learner guide
    Current ISO draft standard
    CCAN -- new CPAN like open source library repository
    3 (different) GNU debugger tutorials: #1 -- #2 -- #3
    cpwiki -- our wiki on sourceforge

  4. #4
    CSharpener vart's Avatar
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    Quote Originally Posted by MK27 View Post
    I presume that's what you were trying to do with your example in the other thread, but it doesn't work!
    Works for me
    Code:
    #include <stdio.h>
    #include <stdlib.h>
    
    int main(void)
    {
    	char sAddr[] = "0x00ac0098";
    	unsigned int uAddr = strtoul(sAddr,NULL,0);
    	void* pAddr = (void*) uAddr;
    
    	printf("&#37;p", pAddr);
    	return 0;
    }
    it prints exactly the same address I have put into the string, of course dereferencing this address will fail - because it is just some random value - low chance to have something available there - put the address of something accessable - and you will have no problem dereferencing it...
    The first 90% of a project takes 90% of the time,
    the last 10% takes the other 90% of the time.

  5. #5
    spurious conceit MK27's Avatar
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    Quote Originally Posted by vart View Post
    Works for me
    Well, it is also somewhat different than your other code -- but thanks thanks thanks vart, that will do my just fine
    C programming resources:
    GNU C Function and Macro Index -- glibc reference manual
    The C Book -- nice online learner guide
    Current ISO draft standard
    CCAN -- new CPAN like open source library repository
    3 (different) GNU debugger tutorials: #1 -- #2 -- #3
    cpwiki -- our wiki on sourceforge

  6. #6
    Banned master5001's Avatar
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    Why are you even using a string literal for this? I just noticed your other thread was using a string literal too. Why not just make it a constant?

    Code:
    #define addr 0x00ac0098
    It is much less overhead.

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