Which, not only is ugly and slow I’d dispute both. A regex or other string parsing method would be uglier and slower. I’m not sure that anything much could be faster than the above. It calls the function and returns. Try/Catch doesn’t introduce much overhead because the most common exception is caught without an extensive … Read more
Short roundup of IEEE-754 floating point numbers (32-bit) off the top of my head: 1 bit sign (0 means positive number, 1 means negative number) 8 bit exponent (with -127 bias, not important here) 23 bits “mantissa” With exceptions for the exponent values 0 and 255, you can calculate the value as: (sign ? -1 : … Read more
rand() can be used to generate pseudo-random numbers in C++. In combination with RAND_MAX and a little math, you can generate random numbers in any arbitrary interval you choose. This is sufficient for learning purposes and toy programs. If you need truly random numbers with normal distribution, you’ll need to employ a more advanced method. This will generate a number … Read more
Best approach, no crazed values, distributed with respect to the representable intervals on the floating-point number line (removed “uniform” as with respect to a continuous number line it is decidedly non-uniform): (*) … check here for subnormal floats Warning: generates positive infinity as well! Choose exponent of 127 to be on the safe side. Another approach which will give … Read more
A “floating point number” is how computers usually represent numbers that are not integers — basically, a number with a decimal point. In C++ you declare them with float instead of int. A floating point exception is an error that occurs when you try to do something impossible with a floating point number, such as divide by zero.
add 0.5 before casting (if x > 0) or subtract 0.5 (if x < 0), because the compiler will always truncate. C++11 also introduces std::round, which likely uses a similar logic of adding 0.5 to |x| under the hood (see the link if interested) but is obviously more robust. A follow up question might be why the float … Read more
From the Floating-Point Guide: What can I do to avoid this problem? That depends on what kind of calculations you’re doing. If you really need your results to add up exactly, especially when you work with money: use a special decimal datatype. If you just don’t want to see all those extra decimal places: simply format … Read more
Use random.uniform(a, b):
You can do it like this: 6 represents the number of digits after the decimal separator.
Neither is more correct than the other. They just represent different values. 1e-9 is 0.000000001; the minus sign applies to the exponent. -1e9 is -1000000000.0; the minus sign applies to the number itself. The e (or E) means “times 10-to-the”, so 1e9 is “one times ten to the ninth power”, and 1e-9 means “one times ten to the negative ninth power”. In mathematical scientific notation, this … Read more