MAC地址加减1算法

please input the mac :
00:1A:A9:AA:BB:CC
new mac for decrease is :00:1A:A9:AA:BB:CB
new mac for increase is :00:1A:A9:AA:BB:CD

#define  BOOL int 
#define  FALSE 0 
#define  TRUE  1 
#include <stdio.h> 
#include <string.h> 
BOOL macDecrease(char * mac) //DECREASE MAC BY ONE 
{ 
    int num=16; 
    while(num>=0) 
    { 
        if('A' == mac[num]) 
        { 
            mac[num]='9'; 
            break; 
        } 
        else if('0' == mac[num]) 
        { 
            mac[num]='F'; 
            num--; 
        }
        else if(':' == mac[num])
        {
            num--;
        }
        else 
        { 
            mac[num]--; 
            break; 
        } 
    } 
    if(-1 == num) 
         return FALSE; //DECREASE FAIL 
    else 
        return TRUE; 
} 
BOOL macIncrease(char * mac) //INCREASE MAC BY ONE 
{ 
    int num=16; 
    while(num>=0) 
    { 
        if('9' == mac[num]) 
        { 
            mac[num]='A'; 
            break; 
        } 
        else if('F' == mac[num]) 
        { 
            mac[num]='0'; 
            num--; 
        }
        else if(':' == mac[num])
        {
            num--;
        }
        else 
        { 
            mac[num]++; 
            break; 
        } 
    } 
    if(-1 == num) 
         return FALSE;  //inclease FAIL 
    else 
        return TRUE; 
} 
void main(int argc, char* argv[]) 
{ 
    char mac[18],macInc[18]; 
    printf("please input the mac :\n"); 
    scanf("%s",mac); 
    strcpy(macInc,mac); 
    if(TRUE == macDecrease(mac)) 
        printf("new mac for decrease is :%s\n",mac); 
    else 
        printf("wrong in decrease\n"); 
    if(TRUE == macIncrease(macInc)) 
        printf("new mac for increase is :%s\n",macInc); 
    else 
        printf("wrong in increase\n"); 
}