beginner in C: void pointer refers to an array of double. How do I read the data?

Hi

I am using code from the hardware manufacturer of this chip in robotics I bought, but I'm a beginner in C.

The code is event driven. After x millisecond an eventhandler is called. This event handler receives a "void *userptr" variable for the user to do whatever they want with it.

In the main() I have declared "double dataset1[10]" and I pass the address on to the eventhandler.

In the eventhandler I need to access the data in dataset1 but I can't get the code right. I believe a typecasting is required here but can't get it right. Can someone tell me how I can access the data in the dataset1 array using the void *usertpr?

for example how do I retrieve the value of dataset1[1] ?

Thanks

In C, a void pointer is implicitly convertible to any other pointer type, so all you should need in the function is

Code:

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  double *data = userptr;
    /*  data[i] can now be accessed for i = 0 to 9 */

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If you insist on an explicit type conversion (aka typecast) then the syntax is

Code:

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  double *data = (double *)userptr;

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If you actually need such a explicit conversion to stop you compiler complaining, then you are actually using a C++ compiler. Note that such an explicit conversion is considered poor form in C.

works great. Thx.