无法将uint64_t正确转换为double。 我想念什么？

Question

To give some background, I'm coding the JVM for Java 8 in C, and I'm trying to print the Double value located in the Constant Pool.

I have two variables uint32_t that represent the high and low value of a double. I'm trying to print this double but I can't figure out what is wrong with my code.

I've tried printing all values to check.

uint64_t high_arg, low_arg, double_value;

high_arg = cp[cpIndex-1].info.Double.high_bytes; // value is = 0x0000000040000000
low_arg = cp[cpIndex-1].info.Double.low_bytes; // value is = 0x0000000000000000
double_value = (high_arg << 32) | low_arg; // value is = 0x4000000000000000
printf("%f\n", (double)double_value);

It prints double:4.61169e+18 but is was supposed to return 2

What am I missing?

Answer 1

@JonathanLeffler明智地指出，解决方案是将表示double的整数转换为double指针，并打印其内容。

printf("%f", *(double *)&double_value);