判断数字
题目:给一个不多于5位的正整数,要求:一、求它是几位数,二、逆序打印出各位数字。
数字倒序输出int-->string-->char[]-->string
//方法一 public static void getNum(){ Scanner scanner = new Scanner(System.in); int num = scanner.nextInt(); int count = 0; //记录位数 int weishu = 0; //得到的每一位 int nixu = 0; //逆序数字 if(num<0||num>99999){ System.out.println("数值不符合要求"); System.exit(0); } do { //这样倒叙太麻烦,采用第二种方式把int转为string,再由string转为char[],再由char[]变为string nixu = nixu*10; //逆序数要*10来放下一位 weishu = num % 10; //在num去掉末位数之前得到末位数 nixu+=weishu; //然后末位数加到逆序数上面 num = num/10; count++; if (num==0) { break; } } while (true); System.out.println("一共有:"+count+"位,逆序为:"+nixu); } //方法二 public static void getNum2(){ Scanner scanner = new Scanner(System.in); int num = scanner.nextInt(); if (num<0||num>99999) { System.out.println("数值不符合要求"); System.exit(0); } if(num >=0 && num <=9) { System.out.println( num + "是一位数"); System.out.println("按逆序输出是" + '\n' + num); } else if(num >= 10 && num <= 99) { System.out.println(num + "是二位数"); System.out.println("按逆序输出是"+revert(num)); } else if(num >= 100 && num <= 999) { System.out.println(num + "是三位数"); System.out.println("按逆序输出是"+revert(num)); } else if(num >= 1000 && num <= 9999) { System.out.println(num + "是四位数"); System.out.println("按逆序输出是"+revert(num)); } else if(num >= 10000 && num <= 99999) { System.out.println(num + "是五位数"); System.out.println("按逆序输出是"+revert(num)); } } //倒序输出 public static String revert(int num){ StringBuilder stringBuilder = new StringBuilder(); String result = Integer.toString(num); //int转string char[] arr = result.toCharArray(); //string转char[] for (int i = arr.length-1; i >=0 ; i--) { stringBuilder.append(arr[i]); //char[]转string } return stringBuilder.toString(); }
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