memcpy() buffer manipulation copies the "count" characters from the array block, "str2" to str1". When the arrays overlap behaviour of this function is undefined, this also returns a pointer to "str1". This function simply copies byte by byte characters of the block from the array.

    void *memcpy(void *str1, void *str2, size_t count);

   #include <stdio.h>
   #include <string.h>
   int main ()
     { 
        char str1[40];
        char str2[]="Memory copy string";
        memcpy (str1,str2,strlen(str2)+1);
        printf ("Array str1 is: %s\nArray 
                  str2 is: %s\n",str1,str2);
        return 0;
     }

   Array str1 is:Memory copy string  
   Array str2 is:Memory copy string

In the above example, this buffer manipulation is used to copy block of contents of "str2" to "str1", the count is same as the length of "str1".