前面为零的整数是什么意思，如何打印? [英] What does an integer that has zero in front of it mean and how can I print it?

问题描述

类测试{公共静态无效主要(字符串参数[]){int a = 011;System.out.println(a);}}

为什么我得到的是 9 而不是 011?

我怎样才能得到 011 作为输出?

解决方案

解决方案:

如果您希望您的整数保持值 11，那么不要花哨，只需分配 11.毕竟，符号不会改变值的任何内容.我的意思是，从数学的角度来看 11 = 011 = 11,0.

int a = 11;

格式仅在您打印时(或将 int 转换为 String 时)才重要.

String with3digits = String.format("%03d", a);System.out.println(with3digits);

格式化程序%03d"用于添加前导零.

或者，您可以使用 printf 方法在 1 行中完成.

System.out.printf("%03d", a);

class test{
  public static void main(String args[]){
     int a = 011;
     System.out.println(a);
  }
}

Why I am getting 9 as output instead of 011?

How can I get 011 as output?

解决方案

The JLS 3.10.1 describes 4 ways to define integers.

An integer literal may be expressed in decimal (base 10), hexadecimal (base 16), octal (base 8), or binary (base 2).

An octal numeral consists of a digit 0 followed by one or more of the digits 0 through 7 ...

A decimal numeral is either the single digit 0, representing the integer zero, or consists of an digit from 1 to 9 optionally followed by one or more digits from 0 to 9 ...

In summary if your integer literal (i.e. 011) starts with a 0, then java will assume it's an octal notation.

Solutions:

If you want your integer to hold the value 11, then don't be fancy, just assign 11. After all, the notation doesn't change anything to the value. I mean, from a mathematical point of view 11 = 011 = 11,0.

int a = 11;

The formatting only matters when you print it (or when you convert your int to a String).

String with3digits = String.format("%03d", a);
System.out.println(with3digits);

The formatter "%03d" is used to add leading zeroes.

Alternatively, you could do it in 1 line, using the printf method.

System.out.printf("%03d", a);

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