void* is literally float, how to cast?

c++ c casting void void-pointers
xNidhogg picture xNidhogg · Mar 9, 2013 · Viewed 14.3k times · Source

So I'm using this C library in my C++ app, and one of the functions returns a void*. Now I'm not the sharpest with pure C, but have heard that a void* can be cast to pretty much any other *-type. I also know that I expect a float at the end somewhere from this function.

So I cast the void* to a float* and dereference the float*, crash. darn!. I debug the code and in gdb let it evaluate (float)voidPtr and low and behold the value is what I expect and need!

But wait, it's impossible to the same during compile time. If I write float number = (float)voidPtr; it doesn't compile, which is understandable.

So now the question, how do I get my float out of this fricking void*?

EDIT: Thanks to H2CO3 this was solved, but I see lots of answers and comments appearing and dissappering not believing that I could do (float)voidPtr in gdb. here is the screenshot.

enter image description here

Answer

user529758 picture user529758 · Mar 9, 2013

Try using pointers:

void *theValueAsVoidPtr = // whatever

float flt = *(float *)&theValueAsVoidPtr;

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