JVAVBigInteger类的使用

import java.math.*;
import java.text.DecimalFormat;
import java.util.Scanner;
public class bignum {
public static void main(String args[]){
BigInteger a,b;
String s;
char op;
Scanner cin=new Scanner(System.in);
while(cin.hasNext()){
a=cin.nextBigInteger();
s=cin.next();
op=s.charAt(0);
if(op == '+'){
b=cin.nextBigInteger();
System.out.println(a.add(b));
}else if(op=='-'){
b=cin.nextBigInteger();
System.out.println(a.subtract(b));
}else if(op=='*'){
b=cin.nextBigInteger();
System.out.println(a.multiply(b));
}/*else if(op=='/'){
b=cin.nextBigInteger();
System.out.println(a.divide(b));
}*/else if(op=='%'){
b=cin.nextBigInteger();
System.out.println(a.mod(b));
}else{
BigDecimal a1,b1,eps;
String s1,s2,temp;
s1=a.toString();
a1=new BigDecimal(s1);
b=cin.nextBigInteger();
s2=b.toString();
b1=new BigDecimal(s2);
int c=cin.nextInt();
eps=a1.divide(b1,c,4);
if(c!=0){
temp="0.";
for(int i=0;i<c;i++) temp+="0";
DecimalFormat gd=new DecimalFormat(temp);
System.out.println(gd.format(eps));
}
else
System.out.println(eps);
}

}
}
}