(面试笔试常考）输入一个IP地址,输入一个整数，输出将IP转化为二进制序列后对应的十进制数，和将整数转化为二进制序列后对应的IP

题目描述

输入一个IP地址,输入一个整数，输出将IP转化为二进制序列后对应的十进制数，和将整数转化为二进制序列后对应的IP

上代码：

import java.util.Scanner; import java.util.Stack; public class IPTransform { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); String ip = scanner.next(); String[] str = ip.split("\\."); int num = scanner.nextInt(); dec(str); //求IP--》》》十进制 ReqIP(num); //求十进制-》》》IP } //将十进制转换为IP,先转为二进制，再转IP; private static void ReqIP(int num) { StringBuffer sb5 = new StringBuffer(); String sb3 = new String(binary2(num)); String[] st = sb3.split("\\."); for (int i = 0; i < st.length; i++) { sb5.append(reqDec(st[i])); if(i < st.length-1){ sb5.append('.'); } } System.out.println(sb5.toString()); } //求ip时的转换二进制，由于与求十进制时的转化有差别，所以重新写了一个方法 private static String binary2(int num) { StringBuffer sb4 = new StringBuffer(); Stack<Integer> stack = new Stack<>(); while (num >= 1){ int a = num%2; num /= 2; stack.push(a); } int cur = stack.size(); int cur2 = 32 -cur; for (int i = 0; i < cur2; i++) { stack.push(0); } int co = 0; while (!stack.empty()){ int re = stack.pop(); sb4.append(re); co++; if(co == 8){ sb4.append('.'); co = 0; } } sb4.deleteCharAt(35); return sb4.toString(); } //将ip转化为十进制 /先将ip转二进制序列再转十进制 private static void dec(String[] str) { StringBuffer sb = new StringBuffer(); int result = 0; for (int i = 0; i < str.length; i++) { int ret = Integer.parseInt(str[i]); String s = binary(ret); sb.append(s); } result = reqDec(sb.toString()); System.out.println(result); } //二进制转十进制 private static int reqDec(String str){ int result = 0; int ai = 0; for (int i = str.length()-1; i >=0; i--) { int index = str.charAt(i) - '0'; result += (int)Math.pow(2,ai)*index; ai++; } return result; } //求二进制序列 private static String binary(int ret) { StringBuffer sb2 = new StringBuffer(); Stack<Integer> stack = new Stack<>(); while (ret >= 1){ int a = ret%2; ret /= 2; stack.push(a); } int cur = stack.size(); int cur2 = 8 -cur; for (int i = 0; i < cur2; i++) { stack.push(0); } while (!stack.empty()){ int re = stack.pop(); sb2.append(re); } return sb2.toString(); } }

运行结果：