numbers

I have a need to create a graph, where the scale of the Y-axis changes depending on the data input into the system. Conceivably this scale could be anywhere from 0-10, 0-100, or even have bottom limit of thousands and an upper limit of millions. To properly determinethe scale of this axis, I need to work out the ratio of Points to Pixels (based on graph height/range). Now a graphs' axis never start at the lowest value and go to the highest, usual practice is to go to the next nearest 2, 5 or 10 (above for upper limit, and below for lower) depending on the range of values. So what I'd like to

I'm trying to write a function in c++ that will return true or false based on a probability given. So, for example if the probability given was 0.634 then, 63.4% of the time the function would return true. I've tried a few different things, and failed. Any help? If you'd like to do this in C++11, you can use its various random number engines, combined with the uniform_real_distribution to provide a good result. The following code demonstrates: #include <random> std::knuth_b rand_engine; // replace knuth_b with one of the engines listed below std::uniform_real_distribution<> uniform_zero_to_one

I need to write a regular expression for taking input like this 23,456,22,1,32767 i.e. No commas allowed at the start or end. Spaces may come before and/or start of comma for e.g. 23, 45,56 ,67 etc. Ranges of each number should be 0-32767. Currently I am using regular expression like this [0-9]+(,[0-9]+)* . This allows for numbers separated by commas only ( not allowing spaces at all), and it does not check for the range of number. It's probably wise to do it in two steps. First check that the range is 0-99999: ^[0-9]{1,5}( *, *[0-9]{1,5})*$ Then parse the string to a list of integers using a

Apparently this is suposed to work in showing if a string is numerical, for example "12.5" == yes, "abc" == no. However I get a no reguardless of the input. std::stringstream ss("2"); double d; ss >> d; if(ss.good()) {std::cout<<"number"<<std::endl;} else {std::cout<<"other"<<std::endl;} You should use an istringstream so that it knows it's trying to parse input. Also, just check the result of the extraction directly rather than using good later. #include <sstream> #include <iostream> int main() { std::istringstream ss("2"); double d = 0.0; if(ss >> d) {std::cout<<"number"<<std::endl;} else