How to avoid rounding with using of strtold

Question

I tried this:

#include <cstdlib>
#include <iostream>

int main ()
{
    char *p;
    long double l = strtold("12312.12345", &p);
    std::cout << l << std::endl; //prints 12312.1
}

demo

How to avoid that kind of rounding?

Answer 1

Your string is correctly parsed. You can verify it in this way:

// Remove the integer part ...
std::cout << (l - 12312) << std::endl;
// ... and you get the fractional part correctly displayed:
// 0.12345

So the reported problem is just a matter of output formatting.