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What's wrong with my memcpy statement?

Posted on 2004-04-01
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Last Modified: 2010-04-15
I have a seemingly simple problem. I just want to copy 100 bytes from my buffer to an absolute memory address of an ARM processor. Let's say that address is 0x100000.

long int AbsAddr = 0x2000000;
char *chbuffer[100]; // my buffer of 100 bytes

memcpy (AbsAddr, chBuffer, 100); // My statement

The C Compiler keeps complaining about incompatible cast. I understand AbsAddr is long int whereas *chbuffer is a char. But both of them are only pointers to char variables. Why pointers also need to have the same cast? I even test this statement and it still doesn't work:

char cTest = 0x01;
*AbsAddr = cTest; // Compiler also complains!




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Question by:Volga
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Expert Comment

by:sunnycoder
ID: 10738394
Hi Volga,

you can cast one pointer to another but mixing longs with pointers without a cast may be too much to ask ... try using void * instead

Sunnycoder
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by:sunnycoder
sunnycoder earned 25 total points
ID: 10738398
Volga,

> But both of them are only pointers to char variables.
No both of them are not pointers .. AbsAddr is a long int and not a pointer ... When you say *AbsAddr, you are dereferencing a long int and not a pointer .... valid enough reason for compiler to complaint

Sunnycoder
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Accepted Solution

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ozo earned 75 total points
ID: 10738447
long int AbsAddr = 0x2000000;
char chBuffer[100]; // my buffer of 100 bytes

memcpy ((char *)AbsAddr, chBuffer, 100);
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Author Comment

by:Volga
ID: 10738550
ozo, thanks for the suggestion. At least you gave me a solution.

SunnyCoder, also thanks for your explanation, however I need a quick solution.
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