What is wrong with this statement? It doesn't copy right.
memcpy(new_board1, board, sizeof(board));
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5"Doesn't copy right" in what way?Sebastian Paaske Tørholm– Sebastian Paaske Tørholm2011-02-12 14:12:44 +00:00Commented Feb 12, 2011 at 14:12
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2Can you show the declarations of board and new_board?jwismar– jwismar2011-02-12 14:13:28 +00:00Commented Feb 12, 2011 at 14:13
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I think nothing, as long as new_board1 is allocatedAugusto– Augusto2011-02-12 14:14:10 +00:00Commented Feb 12, 2011 at 14:14
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2 Answers
memcpy accepts two memory addresses in form of pointers (destination and source) and the number of bytes to be copied. Now, sizeof doesn't return the size of the memory block a pointer points to, but the size of the pointer itself - either 4 bytes on a 32bit OS, or 8 bytes on a 64bit OS.
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pmg
sizeof returns the size, in bytes, of the object passed as its parameter. In case only a type is passed it returns the size of an object of that type. int *ptr = malloc(1000 * sizeof *ptr); int data[1000]; memcpy(ptr, data, sizeof data);
user611775
Whether that is 2, 4 or 8 bytes is completely inplementation-dependent. Your OS could be 64-bit while still getting sizeof(void*)=4.
sizeof(board) gives you the size of the pointer itself, not the size of whatever it points at. You should replace it by the actual number of bytes you want to copy from board to new_board1. Without knowing how boardand new_board1 are declared, I cannot help you find that number.
