![]() * letter characters may be in either upper or lower case. * Generates a printable binary representation of an input number * int convert_num(char const* s, int b, char** o) * convert_num - convert a numerical string (str) of base (b) to ![]() Making it really work is an exercise for the reader. It probably contains bugs in edge cases, but it does compile and work as expected at least for positive numbers. How to Convert a String to an Integer in Java Using Integer. When added to another integer, we got a proper addition: agetoint + 20. If a C/C++ solution is acceptable, I believe that the following is what you are looking for is something like the following. In order to convert the age variable to an integer, we passed it as a parameter to the parseInt () method Integer.parseInt (age) and stored it in a variable called agetoint. If you really don't need arbitrary precision, then take advantage of the runtime. I'm not sure if a lookup table approach is possible or not. I wrote this before your clarifying comment so it probably isn't quite is applicable. Then, you are only reduced to adding n numbers, rather than multiplying and adding n numbers (plus the cost of the memory of the lookup table) The best you can do is have a lookup table of the form: (a,b) where a is the digit position, and b is the digit (0.9). You'll notice that the multiplication never gets simple, so you can't have any lookup tables and do bitshifts and ors, no matter how big you group them. So if you have the lookup table of A = (0b000 to 0b111), then the multiplication is always by 1 and some trailing zeros, so the multiplication is simple (just shifting left). The reason that it is possible for base 8 (and 16) is that the way the conversion works is following: ![]() This is not possible in bases that aren't powers of two to convert to base-2. I am aware of the multiply and add solution but since these are arbitrary length numbers, the multiply and add operations are not free so I'd like to avoid them, if at all possible. ![]() I know that for base 10, you can't just give it one digit at a time, so the solution would likely have to lookup a group of digits at a time. I was curious if anyone had any clever way to figure out how to generate a generic look up table for Base X -> Base 2. It's definitely not so obvious with base 10, though. I know that I could write the algorithm like atoi does and do a bunch of multiplies and adds, but for this specific problem I'm trying to see if I can do it with a look up table. However, my problem is that I want to do this look up table method for odd bases, like base 10. I can simply use a lookup table for each digit to get a series of bits. I have found that this is simple for binary, octal, and hexadecimal. My solution now does what the atoi() function does, but I was curious purely out of academic interest if a lookup table solution is possible. ** * Java Program to show how to convert a floating point double * value to a long in Java.I want to be able to take, as input, a character pointer to a number in base 2 through 16 and as a second parameter, what base the number is in and then convert that to it's representation in base 2. ![]() If you are using Eclipse IDE, just copy-paste the code and it will automatically create the correct Java source file and packages, provided you keep your mouse on a Java project. It is simple to convert String to BigInteger in java.We can simply use BigInteger’s constructor to convert String to BigInteger. You can use this sample program to quickly run and check how it works. In this one program, we have used all three ways explained in the above paragraph. Here is a complete example of converting a floating-point double value to an integral long value in Java. You can use any of these methods to convert double to long in Java. One more advantage of this method is that it works for wrapper classes Long and Double as well. So it depends on double value, if the decimal point is 0.5 or greater then it will be rounded to the next long value otherwise to the previous or lower long value. It doesn't give the same result as a cast. Now, if you need rounding you can use Math.round() method to round a floating-point number into the nearest integral number This will be faster than going via the wrapper classes - and more importantly, it's more readable. Here is the code example of casting a double to long in Java, you will notice in both cases result is the same.Ĭasting double to long just truncate trailing zero. Use this method only if you are getting a Double wrapper object. So if you have a primitive double, just directly cast it to long. ![]()
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