Octal Fractions

Description

Fractions in octal (base 8) notation can be expressed exactly in decimal notation. For example, 0.75 in octal is 0.953125 (7/8 + 5/64) in decimal. All octal numbers of n digits to the right of the octal point can be expressed in no more than 3n decimal digits to the right of the decimal point. 

Write a program to convert octal numerals between 0 and 1, inclusive, into equivalent decimal numerals.

Input

The input to your program will consist of octal numbers, one per line, to be converted. Each input number has the form 0.d1d2d3 … dk, where the di are octal digits (0..7). There is no limit on k.

Output

Your output will consist of a sequence of lines of the form 

0.d1d2d3 … dk [8] = 0.D1D2D3 … Dm [10]

where the left side is the input (in octal), and the right hand side the decimal (base 10) equivalent. There must be no trailing zeros, i.e. Dm is not equal to 0.

Sample Input

0.75
0.0001
0.01234567

Sample Output

0.75 [8] = 0.953125 [10]
0.0001 [8] = 0.000244140625 [10]
0.01234567 [8] = 0.020408093929290771484375 [10]

Source

Southern African 2001

原题链接:http://poj.org/problem?id=1131


题意:输入一个8进制的小于0的数,将其转换为10进制.


PS:原先在API中找输入为8进制的方法,但是没有找到!!网上看了别人的代码,确实没有!都用模拟,但比C/C++好多了
转换方式:
例如:
0.75[8]—->7*8^(-1) + 5*8^(-2)=0.953125 [10]

AC代码:

import java.math.BigDecimal;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		while (sc.hasNext()) {
			String str = sc.next();
			BigDecimal ans = new BigDecimal(0);
			BigDecimal base = new BigDecimal(1);
			int length = str.length();
			for (int i = 2; i < length; i++) {
				base = base.divide(new BigDecimal(8));
				BigDecimal t = new BigDecimal(str.charAt(i)-'0');
				ans = ans.add(t.multiply(base));
			}
			System.out.println(str+" [8] = "+ans+" [10]");
		}
	}

}