write your own memmove program without overlapping constrain.

1:  #include <stdio.h>  
2:  #include <string.h>  
3:  void * my_memmove(char *dest,char *src,int count)  
4:  {  
5:    char *temp;  
6:    char *s;  
7:    if ( dest <= src) {  
8:      temp = dest;  
9:      s = src;  
10:      while(count--)  
11:        *temp++ = *s++;  
12:    } else {  
13:      temp = dest;  
14:      temp += count;  
15:      s = src;  
16:      s += count;  
17:      while(count--)  
18:        *--temp = *--s;  
19:    }  
20:    return dest;  
21:  }  
22:  main()  
23:  {  
24:    char str[100] = "abcdefghijklmnopqrstuvwxyz";  
25:    my_memmove(str+5,str,4);  
26:    printf("my_memmove = %s\n",str);  
27:    strcpy(str,"abcdefghijklmnopqrstuvwxyz");  
28:    memmove(str+5,str,4);  
29:    printf("sys_memmove = %s\n",str); // compare with original memmove  
30:    strcpy(str,"abcdefghijklmnopqrstuvwxyz");  
31:    memcpy(str+5,str,4);  
32:    printf("sys_memcpy = %s\n",str); // and memcpy to check overlap  
33:  }