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c++bitconverters

How to convert bytes from uint64_t to double?

I have binary file from which I read uint64_t val (using little-endian). Now I want to convert this uint64_t to double (not just casting, but exactly the number that would be double if I entered it from the file). So the should has the same bit representation. How I should do this?

Solution

  • Simple portable way:

    uint64_t u64 = read_from_file();
double d;
memcpy(&d, &u64, sizeof(d));

    Most compilers will generate just a couple of instructions for this.