为什么 double d = (byte) a 的计算结果是 1.0 ?
Why does double d = (byte) a compute to 1.0?
int a = 257;
int b = 4;
int c = 3;
int e = 2;
double d = (byte)a + b / c / e;为什么 double d = (byte) a 的计算结果是 1.0 ?
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micro
12 八月 2023, 13:22
byte类型为1字节是8位，int类型的a在内存中占据32位，a=257H =(00000000 00000000 00000001 00000001)B(H是十进制后缀，B是二进制后缀)，这样将int类型的值强制类型转换为byte时会自动截取后面的8位，即00000001B，也就是十进制的1，最后又转为了double类型所以是小数1.0
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Guadalupe Gagnon
11 八月 2023, 13:34
Its because bytes are only 8 bits, with a min value of -128 and a max value of 127. The binary of 257 is:
100000001
That is 9 bits long. When casting an int to a byte only the first 8 bits (the amount of bits a byte has) of the int are converted to the byte, in this case only the first 1. So the binary 00000001 is equal to 1, which in your code is then converted to a double, which is1.0.
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