c语言里如何将字符串fff转换成16进制的fff

#define N 8 void tran(int num,int k) {int arr[N],i;for (i=0;i =0;i--)switch (arr[i]){case 10: printf("A");break;case 11: printf("B");break;case 12: printf("C");break;case 13: printf("D");break;case 14: printf("E");break;case 15: printf("F");break;default: printf("%d",arr[i]);}printf("\n\n\n"); } void main() {int num,choo; loop: printf("请选择功能：0.退出 1.十进制转二进制 2.十进制转八进制 3.十进制转十六进制\n");scanf("%d",&choo);switch (choo){case 1:printf("请输入要转换的十进制数：");scanf("%d",&num);tran (num,2);goto loop;case 2:printf("请输入要转换的十进制数：");scanf("%d",&num);tran (num,8);goto loop;case 3:printf("请输入要转换的十进制数：");scanf("%d",&num);tran (num,16);goto loop;case 0:break;default :printf("输入有误！请重新输入！\n");goto loop;} }老铁请采纳