How to use random precision numbers

Question

Hello I need help writing my program. I am trying to figure out how I should make it so when I type two range numbers (one is a maximum and one is a minimum) which the program will recognize and output a random number in between one of them. So far I have figured it out but it works only for whole numbers, I cant seem to find a way for those numbers to be with precision of 2 lets say.

#include "pch.h"
#include <iostream>
#include <iomanip>
#include <cstdlib>
#include <ctime>

using std::cout;
using std::cin;
using std::endl;

int main()
{
int  a, b, c, d;
srand(time(0));
cout << "Welcome to the game." << endl;
cout << "Please enter number range" << endl;
cout << "Highest number:";
cin >> c;
cout << "Lowest number:";
cin >> d;
b = d + (rand() % (c - d + 1));
cout << "Enter your guess:";
cin >> a;
unsigned int count = 0;
while (a < b) {
    cout << "Your number is lower than the correct one." << endl;
    cout << "Please try again:";
    cin >> a;
    count++;
}
while (a > b) {
    cout << "Your number is higher than the correcnt one." << endl;
    cout << "Please try again:";
    cin >> a;
    count++;
}

cout << "Your number is the correct one!!! You guessed it on " << count << " time" << endl;
return 0;

}

Possible duplicate of [C++ random float number generation](https://stackoverflow.com/questions/686353/c-random-float-number-generation) — Rhathin, Oct 08 '18 at 15:13
Note that your program doesn't do what you probably think it does. If you guess too high and then too low, it will tell you that you guessed correctly. — Max Langhof, Oct 08 '18 at 15:13
This doesn't address the question, but do you really need the extra stuff that `std::endl` does? `'\n'` ends a line. — Pete Becker, Oct 08 '18 at 15:16
Forgot to mention that I am a beginner, I have just started studying c++ yesterday. Every suggestion would be a good thing for me. — Mitko, Oct 08 '18 at 15:19
C++ does not have a "precision of 2" data type, as it does integer types. You should read up on C++ floating point types, and possibly on decimal type libraries. It's not clear from your question which you are pursuing, so I am not closing this as the proposed duplicate. — Drew Dormann, Oct 08 '18 at 15:22
https://en.cppreference.com/w/cpp/numeric/random/uniform_real_distribution — pptaszni, Oct 08 '18 at 15:26
BTW, floating point variables are stored internally with maximum precision. You can *output* them with whatever precision you want. If you want the values stored with a given precision, you'll have to truncate. — Thomas Matthews, Oct 08 '18 at 16:42

score 1 · Answer 1 · answered Oct 08 '18 at 15:25

You can use std::uniform_real_distribution to generate random floating point:

std::random_device device;
std::mt19937 generator(device());
std::uniform_real_distribution<> distribution(least, greatest);
double a_random_number = distribution(generator);

I cant seem to find a way for those numbers to be with precision of 2 lets say.

Simply round the result to nearest value.

But be aware that typical floating point representations cannot precisely represent all decimal numbers such as 0.1 etc.

How to use random precision numbers

1 Answers1