十六进制转二进制用c语言怎么做呢，那就来我这看看吧

#include<stdio.h>
#include<string.h>
int main()
{char ch;

while((ch=getchar())!='\n')
	{		
	switch(ch)	
		{			
		case '0':  printf("%d%d%d%d",0,0,0,0);  break;
		case '1':  printf("%d%d%d%d",0,0,0,1);  break;			
		case '2':  printf("%d%d%d%d",0,0,1,0);  break;			
		case '3':  printf("%d%d%d%d",0,0,1,1); break;			
		case '4':  printf("%d%d%d%d",0,1,0,0);  break;			
		case '5':  printf("%d%d%d%d",0,1,0,1);  break;			
		case '6':  printf("%d%d%d%d",0,1,1,0); break;			
		case '7':  printf("%d%d%d%d",0,1,1,1);  break;			
		case '8':  printf("%d%d%d%d",1,0,0,0); break;			
		case '9':  printf("%d%d%d%d",1,0,0,1); break;  			
		case 'A':  printf("%d%d%d%d",1,0,1,0);  break;			
		case 'B':  printf("%d%d%d%d",1,0,1,1);  break;			
		case 'C':  printf("%d%d%d%d",1,1,0,0);  break;			
		case 'D':  printf("%d%d%d%d",1,1,0,1);  break;			
		case 'E':  printf("%d%d%d%d",1,1,1,0);  break;			
		case 'F':  printf("%d%d%d%d",1,1,1,1);  break;
	}	
  }		
		return 0;
}