Question

If void * is a pointer to void is a "generic" pointer type, and a void * can be converted to any other pointer type * without an explicit cast, why in the ,myarrcopy function the malloc is created like char and not like void? if we are going to work with different type of arrays? Here is de program:

 *This is a function that make a copy of  any given array.
 * We then use this function make a copy of char array, 
 * int array, and double array. Then print out three arrays
 * to check the result
*/
#include <stdio.h>
#include <stdlib.h>

// This function will copy any type of array
// and return a pointer to it
void* myarrcopy(void *arr, size_t num_elmts, size_t size_elmt)
{
        // allocate memory as char pointer
        size_t total_bytes = num_elmts * size_elmt;
        char* result = malloc(total_bytes);
        char* c = arr;
        // copy over the array memory char by char
        for(int i = 0; i < total_bytes; i++)
                result[i] = c[i];
        // return a memory pointer 
        return (void *) result;
}  

int main(int argc, char *argv[]){
        int i;
        char charArr[] = {'A', 'B', 'C', 'D', 'E'};
        int intArr[] = {1, 2, 3, 4, 5};
        double doubleArr[] = {1.1, 2.22, 3.333, 4.4444, 5.55555};
        
        /*copy and print out the char array */
        char* cptr = myarrcopy(charArr, 5, sizeof(char));
        for(i = 0; i < 5; i++)
                printf("%c\t", cptr[i]);
        printf("\n"); 
        
        /*copy and print out the int array */
        int* iptr = myarrcopy(intArr, 5, sizeof(int));
        for(i = 0; i < 5; i++)
                printf("%d\t", iptr[i]);
        printf("\n");
        
        /*copy and print out the double array */
        double* dptr = myarrcopy(doubleArr, 5, sizeof(double));
        for(i = 0; i < 5; i++)
                printf("%f\t", dptr[i]);
        return EXIT_SUCCESS;
}

Answer 1

Please pay much attention to the fact that, there are data and pointers type.. The data types are int, float, char, boolean etc.. Which the pointer types point to some kind of data.. 
The data types have varying sizes like int is of 4 bytes, boolean of 1 byte and so on.. While the pointers are essentialy a address, which just tell that some memory location is a starting address for some data which we kept. Now what kind of data is kept on the memory is determined by type of pointer.. Like int pointer will point to data in memory which is of integer type, the long pointer points to the data which is of type long.. and so on.. But essentially if you look, all pointers are nothing but a reference to the start of the memory, Due to which their sizes are always same.. no matter what kind of data they are pointing to..

Hence, Either we allocate memory for storing char pointers, or void pointers, or long pointers, they all are going to take the same memory.. Also, malloc just allocates the memory.. you are free to store anything in that memory.. So You are not bound to store only character pointers if you are allocating with sizeof(char*)



hope it clarifies your doubts.. feel free to ask if anything is not clear.

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