I've read that the difference between calloc and malloc is that calloc initializes the memory to the default value of the type declared.
calloc() will initialize the entire allocated memory range to zero. It has nothing to do with what type you are casting to.
malloc() leaves the contents of the memory in an unspecified state.
The calloc function does not initialize memory to the default value for a given type, and in fact it can't because it knows nothing regarding the type that the memory will be used for.
What it does do is set the memory to all bits 0. On most implementations you're likely to come across, this means that integer and floating point types will have the value 0 and that pointer types will be NULL. With regard to structs and/or arrays, this would apply to any members, and additionally any padding within a struct would also have all bits set to 0.
calloc()initializes memory with all bytes zero. So typically all values are initialized zero and all pointersNULL(whereNULLis all bytes zero -- which I know of no case that isn't true, but also isn't guaranteed).malloc()does no initialization whatsoever.