思路：1、正數 --> (該數%16) 余數 >= 10, 余數 < 10;

　　　2、負數

　　　3、零

//十進制轉化為十六進制 
//逆序存儲在一個字符串數組中 
#include<stdio.h>
char* TenToSixteen(int ten){
    char str[20];
    int i = 0,w = 0,temp = ten,status;
    if(temp>= 0) status = 1;
    else status = 0;
    
    switch(status){
        case 1:    //當為正數 
            if
 
(ten==0)     str[w++] = ‘0‘;
            else{
                while(temp> 0){
                int elem = temp%16;
                if(elem>9){
                    elem = elem -10 +‘A‘;
                    str[w++] = elem;    
                }
                else    str[w++] = elem + ‘0‘;
                temp 
 
= temp/16;
                }
            }
            break;
            case 0:    //當為負數 
                temp = -temp;
                while(temp> 0){
                int elem = temp%16;
                if(elem>9){
                    elem = elem -10 +‘A‘;
                    str[w++] = elem;    
                }
                
 
else    str[w++] = elem + ‘0‘;
                temp = temp/16;
                }
                str[w++] = ‘-‘;
            break;
            default :printf("error!\n");
    }
    
//打印十六進制的數 
    for(i = w-1;i>=0;i--){
        printf("%c",str[i]);    
    }
}

十進制轉十六進制