Given datatype of two variable as an integer value and address of two variables as a void pointer to the function common_swap(). Do swap the values pointed by the two pointer variables.  The integer value from 1 to 6 means the datatype. 1. char(%c) 2. short int(%hd) 3.long int(%ld) 4. long long int(%lld) 5. float(%f) 6. double(%lf).

Here is a C function that swaps the values pointed by two void pointers. The function uses a temporary buffer for swapping and the size of the buffer is determined by the datatype:

#include <stdio.h>
#include <string.h>

void common_swap(void *vp1, void *vp2, int datatype) {
    char buffer[16];

    switch(datatype) {
        case 1: // char
            memcpy(buffer, vp1, sizeof(char));
            memcpy(vp1, vp2, sizeof(char));
            memcpy(vp2, buffer, sizeof(char));
            break;
        case 2: // short int
            memcpy(buffer, vp1, sizeof(short int));
            memcpy(vp1, vp2, sizeof(short int));
            memcpy(vp2, buffer, sizeof(short int));
            break;
        case 3: // long int
            memcpy(buffer, vp1, sizeof(long int));
            memcpy(vp1, vp2, sizeof(long int));
            memcpy(vp2, buffer, sizeof(long int));
            break;
        case 4: // long long int
            memcpy(buffer, vp1, sizeof(long long int));
            memcpy(vp1, vp2, sizeof(long long int));
            memcpy(vp2, buffer, sizeof(long long int));
            break;
        case 5: // float
            memcpy(buffer, vp1, sizeof(float));
            memcpy(vp1, vp2, sizeof(float));
            memcpy(vp2, buffer, sizeof(float));
            break;
        case 6: // double
            memcpy(buffer, vp1, sizeof(double));
            memcpy(vp1, vp2, sizeof(double));
            memcpy(vp2, buffer, sizeof(double));
            break;
    }
}

This function uses the memcpy function to copy the contents of the memory area pointed to by vp1 to the temporary buffer, then copies the contents of the memory area pointed to by vp2 to vp1, and finally copies the contents of the temporary buffer to vp2. The size of the memory areas to be copied is determined by the datatype.