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22 / 2
11
余 0
11 / 2
5
余 1
5
/ 2
2
余 1
2
/ 2
1
余 0
1
/ 2
0
余 1

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0.8125x2=1.625
取整1，小数部分是0.625
0.625x2=1.25
取整1，小数部分是0.25
0.25x2=0.5
取整0，小数部分是0.5
0.5x2=1.0
取整1，小数部分是0，结束

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public static String decimal2Binary(double value) throws Exception {
// 整数部分的值
int in = (int) value;
System.out.println("The integer is: " + in);
// 小数部分的值
double r = value - in;
System.out.println("The decimal number is: " + r);
StringBuilder stringBuilder = new StringBuilder();
// 将整数部分转化为二进制
int remainder = 0;
int quotient = 0;
while (in != 0) {
// 得商
quotient = in / 2;
// 得余数
remainder = in % 2;
stringBuilder.append(remainder);
in = quotient;
}
stringBuilder.reverse();
stringBuilder.append(".");
// 将小数部分转化为二进制
int count = 32; // 限制小数部分位数最多为32位，如果超过32为则抛出异常
double num = 0;
while (r > 0.0000000001) {
count--;
if (count == 0) {
throw new Exception("Cannot change the decimal number to binary!");
}
num = r * 2;
if (num >= 1) {
stringBuilder.append(1);
r = num - 1;
} else {
stringBuilder.append(0);
r = num;
}
}
return stringBuilder.toString();
}

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public static void main(String[] args) {
try {
String s = decimal2Binary(22.8125);
System.out.println("The result is: " + s);
} catch (Exception e) {
e.printStackTrace();
}
}

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The integer is: 22
The decimal number is: 0.8125
The result is: 10110.1101