[C][important] Copy string to char pointer

#include<stdio.h>

int main()
{
    void *data = NULL;
    char tmpdata[128] = {"\0"};
    char *a = NULL;
    int len = 0;

    sprintf(tmpdata,"HAPPY");

    /*allocate memory to char pointer*/
    a = malloc(128);

    strcpy (a,tmpdata);
    len = (unsigned short) strlen(a);
    data=(void *)a;
    printf("%s %d\n",a ,len);

    /*Free memory*/
    free(a);

    return 0;
}

Result :

HAPPY 5