Question

for example in this code:

double **Data, *DataT;
Data = (double **)malloc(3*sizeof(double *)+3*12*sizeof(double));

I just read that malloc allocates memory from the heap. But i could not find what that (double **) meant in front of the malloc.
There is a line of code directly after this as well that i have seen this in.

for (i = 0, DataT = (double *)(Data+3); i < 3; i++, DataT += 12)

Here there is a (double *) in front of Data+3

Could you please explain to me what that does?
Thank you

Answer 1

malloc() returns type void *, while your pointer is of type double * or double **. The operator before malloc – looking like (type) – is the type conversion operator, needed to convert malloc’s return value to the type of the pointer you are using.