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I am trying to store a large amount of boolean information that is determined at run-time. I was wondering what the best method might be.
I have currently been trying to allocate the memory using:
pStatus = malloc((<number of data points>/8) + 1);
thinking that this will give me enough bits to work with. I could then reference each boolean value using the pointer in array notation:
pStatus[element]
Unfortunately this does not seem to be working very well. First, I am having difficulty initializing the memory to the integer value 0. Can this be done using memset()? Still, I don't think that is impacting why I crash when trying to access pStatus[element].
I am also not entirely convinced that this approach is the best one to be using. What I really want is essentially a giant bitmask that reflects the status of the boolean values. Have I missed something?
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In C, dynamic memory is allocated from the heap using some standard library functions. The two key dynamic memory functions are malloc() and free(). The malloc() function takes a single parameter, which is the size of the requested memory area in bytes. It returns a pointer to the allocated memory.
In dlmalloc , the smallest allowed allocation is 32 bytes on a 64-bit system. Going back to the malloc(1) question, 8 bytes of overhead are added to our need for a single byte, and the total is smaller than the minimum of 32, so that's our answer: malloc(1) allocates 32 bytes.
1 Integers. Integers are commonly stored using a word of memory, which is 4 bytes or 32 bits, so integers from 0 up to 4,294,967,295 (232 - 1) can be stored.
...thinking that this will give me enough bits to work with. I could then reference each boolean value using the pointer in array notation:
pStatus[element]
element is addressing bytes, not bits. You want something like:
pStatus[element/8] & (1 << (element % 8))
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