C++ :: Generating Sums Of Random Numbers

Sep 19, 2014

I'm trying to create a code that generates random numbers and spits out a sum average and lowest and highest number. I am stuck on the sum however and once I get that I think the average will fall into place. Here's what I have.

#include <iostream>
#include <iomanip>
#include <ctime>
#include <math.h>
using namespace std;

[Code] ....

I've noticed that it's almost always off by 1 or 3 for whatever reason

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C :: Generating Random Numbers

Oct 19, 2014

I have a program that generates random numbers. After the random number is generated, the program asks if you want to generate another random number. However, if you generate another random number, it is always the same as the first random number. How can I fix this?

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C++ :: Generating Big Random Numbers In C

Feb 16, 2013

I want to generate big random numbers in C(not C++ please).By "big" I mean integers much bigger than srand(time(NULL)) and rand() functions' limit(32767).

I tried writing: (note:I am not able to see "code" tag button in this editor,so I am not using it)

//****
int randomnumber;
srand( time(NULL) );
randomnumber = (( rand() % 33 ) * ( rand() % 33 ) * ( rand() % 33) * ( rand() * 33) * (rand() % 33 )) + 1
//****

But I have doubts about it's randomness quality.Also there is another problem,the program can't know the maximum random number it should use before user input,so maximum random number may need to use much smaller maximum random number according to user input.

Is there a better algorithm to create big random numbers in C?

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C++ :: Generating Big Random Numbers In C

Feb 15, 2013

I want to generate big random numbers in C(not C++).By "big" I mean integers much bigger than srand(time(NULL)) and rand() functions' limit(32767).

I tried writing: (note:I am not able to see "code" tag button in this editor,so I am not using it)

//****
int randomnumber;
srand( time(NULL) );
randomnumber = (( rand() % 33 ) * ( rand() % 33 ) * ( rand() % 33) * ( rand() * 33) * (rand() % 33 )) + 1
//****

But I have doubts about it's randomness quality.Also there is another problem,the program can't know the maximum random number it should use before user input,so maximum random number may need to use much smaller maximum random number according to user input.

Is there a better algorithm to create quality big random numbers in C?

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C++ :: Generating Random Numbers In Parallel

Nov 8, 2013

I generate a series of random numbers in parallel (using OpenMP), but depending on what number of threads I invoke, I get a different result. From that I conclude that I have made an error somewhere!

Here is the MWE, which generates a number between 0..1 and increments a variable if the generated variable is larger than 0.5:

Code:
#include <random>
typedef std::uniform_real_distribution<double> distr_uni;
#define max_threads 1
using namespace std;

[Code] ....

When I set max_threads=1 I get 50027, but when max_threads=60 (on a machine that supports it....) I get 50440.

The sensitive RNG and its engine I have declared within the parallelized area, so it's not really clear to me where the error can possibly be.

Looking for error that is apparently there?

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C :: Generating Random Numbers Without Repeating?

Sep 20, 2014

Inside my loop is this

srand(time(NULL))
a=rand()%10;

So it will generate numbers again and again as the loop goes on but it always repeat some numbers. My question is, how would you generate numbers without repeating? Somebody told me that i have to use auto increment, but i really have no idea about that.

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C++ :: Program That Keeps Generating Two Random Numbers Between 1 And 10

May 6, 2013

#include <ctime>
#include <iostream>
#include <cstdlib>
using namespace std;
int main() {

[Code] ....

Write a program that keeps generating two random numbers between 1 and 10 and asks the user for the product of the two numbers, e.g.: "What is 4 x 6?". If the user answers correctly, the program responds with "Right!"; otherwise, it displays: Wrong! 4 x 6 = 24.

Generate as many pairs of numbers as specified and get the answers from the user for each. If at any time, both numbers are the same as last time, generate two new numbers before asking for the answer. Continue generating 2 new numbers until at least one is different from last time.

After presenting the number of pairs of numbers specified and getting the answers, display how many the user got right; e.g.: You got 4 of 5 right. Then, ask if he or she wants to play again, like so: "Do you want to play again? [y/n]". If the user answers with 'y' or 'Y', it again reads the number of questions to ask and generates that many pairs of numbers and reads the answers like before. If the answer is n or N, it quits generating numbers. If the answer is anything but y, Y, n or N, it tells the user to enter one of those letters until it is.

When the user decides to quit and has got less than 75% of all the questions right, the program displays the multiplication table (1x1 through 10x10) before terminating.

After displaying the table, randomly generate two numbers between 1 and 10, display their product and first number and ask the user to guess the second as more practice. For example, the program will generate 7 and 9 and will display 63 and 7 and the user must guess the second number (i.e.: 9). Do this 3 times. Do not repeat code. Use a loop to do this 3 times.

Use a nested for loop to display the table; a bunch of cout statements will not be acceptable. You must also use a loop for any part that calls for repetition such as generating 5 pairs of numbers.

The following is a sample interaction between the user and the program:

Enter the number of questions to ask: 5

1. What is 3 x 9? 27
Right!

2. What is 2 x 7? 14
Right!

3. What is 8 x 9? 63
Wrong! 8 x 9 = 72

4. What is 6 x 3? 21
Wrong! 6 x 3 = 18

5. What is 2 x 9? 18
Right!

You got 3 out of 5 right which is 60%.

Play agian? [y/n] n

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C# :: Generating Unique Random Numbers In The Range

Apr 28, 2014

We had to generate random, unique numbers in the range [1,15]. But running the program for several times showed a bug: It wouldn't always generate a new number for every repeated number. I can't figure out the problem, especially since it works half the time and I can't figure out what's making it work some times and not others.

bool flag1 = true, flag2 = true, flag3 = true;
int i, j = 1;
int[] A = new int[11];
Random rnd = new Random();
A[0] = rnd.Next(1, 15);
Console.WriteLine("1. = " + A[0]);

[Code] .....

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C++ :: Timer Function - Generating Seed For Random Numbers

Nov 14, 2014

for (int i=0; i<15; i++)
{
nx[i]=rand()%8+1;
printf("%d",nx[i]);
}

I want to the function of timer "srand(time(NULL))" to generate seed for random numbers. By running this for loop,I think I should expect random numbers ranging from 1 to 8.However, I get some wried numbers from the console window like 88,044,077,066,088,088,066,022,044,044,088,022,033,66814990522,-156026525933,1606416712. One more thing,I think I am going to have 15 outputs, but why I get 16 instead every time.

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C++ :: Divide Set Of Numbers Into Two Subsets Where Difference Between Sums Of Subset Is Minimal

Feb 28, 2013

The problem is that you have a set of numbers and you need to divide that set into two subsets where the difference between the sums of the subset is minimal.

Example: a set of numbers {1,5,9,3,8}, now the solution is two subsets, one subset with elements {9,3} and the other {8,5,1} the sum of the first one is 13 and the sum of the second is 13 so the difference between the sums is 0. The result shows the difference between the sums.

Another example: a set of numbers where the difference between the subsets cannot be zero, {9 51 308 107 27 91 62 176 28 6}, the minimal difference between the two subsets is 2.

I want to know how the function finds the two subsets, it works great because I've tested it for up to 300 inputs which sum adds up to 100,000.

Code:
#include <iostream>
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <limits.h>
using namespace std;
int BalancedPartition ( int a[] , int n ) {

[Code] ....

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C++ :: Generating Random Integers?

Jun 9, 2013

I'm creating a game in C++ and need to generate random numbers. I know about

int main()
{
srand(time(NULL)); //Initialises randomiser or sum' like that
int x=rand%10; //Generates from 0-9
cout<<x;
}

Now, I need the best way to generate random numbers. Do I call "srand(time(NULL));" every time I want to randomise? What is the best method to generate a nearly perfect random number?

I may need to call a randomiser more than once a second, so taking second as seed (I believe that's what srand(time(NULL)); does).

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C :: Generating Random And Different Number In Array

Nov 30, 2014

How to generate random and different number in a range. This is my code:

Code:
#include <stdio.h>#define n 8
#define m 7
int main() {
int i,j,a[n][n];
printf("Relaxed Latin Square (%d,%d)

[Code] .....

When I executed that code, the number is random but not different.

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C++ :: Generating String Of Random Letters

May 1, 2014

My problem says: Have the user enter a number from 1-80 then print out a string of random letters(a to z lowercase) of that length.

I have been able to enter the number and output the correct amount of letters but i can't figure out how to get them to be in a random order and not in alphabetical. Here is what I have so far.

#include <iostream>
using namespace std;
int main() {
int i=0;
int num;
cout<<"How many letters do yu want in your random string?";

[Code]....

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C++ :: Generating Random Number Of Normal Distribution

Mar 12, 2013

I am generating random number of normal distribution (0,1) but i suspect maybe I have done it wrong. The generator I use right now is

srand(time(0));
std::random_device rd;
std::mt19937 gen(rd());
std::default_random_engine generator;
std::normal_distribution<double> distribution(0,1);

Am I doing the right thing? Whether this is a real random number generator?

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C++ :: Hangman Game - Generating Random Number

Sep 12, 2013

I am recreating a hangman game. I'm trying to generate a random number to choose which word from my words list to use and I've done it a billion times before just like this. So, here's my code:

#include <iostream>
#include <cstdlib> //standard library.
#include <ctime> //for random.
#include <fstream> //for reading and writing to a file.
#include <string>
using namespace std;
int main() {
int num_words;
string word[num_words];

[Code] .....

I have the text file "words.txt" info below.

5
dog
cat
horse
pig
bird

If I run the program as it is, I get a segmentation fault core dumped error, however, if I take all the stuff that reads in the words from the words.txt file, like so:

#include <iostream> //every program has this.
#include <cstdlib> //standard library.
#include <ctime> //for random.
#include <fstream> //for reading and writing to a file.
#include <string>

[Code] ....

it works correctly and generates a random number.

I'm using Linux Mint.

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C++ :: Generating All Possible Numbers In Base V Of P Digits

Apr 23, 2012

I'm sure this is pretty simple, but any way to do this. Essentially if I have an array with P collumns and V^P rows, how can I fill in all the combinations, that is, essentially, all possible numbers in base V of P digits.

For example, for P=3 and V=2

000
001
010
011
100
101
110
111

Keep in mind that this is an 2 dimensional array, not an array of ints.

For P=4 and V=3.

0000
0001
0002
0010
0011
0012
....

Having this array generated, the rest of work for what I'm trying to develop is trivial

This is a code I've written that should do the trick, but for some reason it gives this error on compiling:

"main.cpp:65: error: invalid types `double[3][9][double]' for array subscript"

Code:
for(i=0;i<P;i++) {
for(j=0;j<pow(V,i);j++) {
for(k=0;k<V;k++) {
for(l=0;l<pow(V,(P-i-1));l++) {
a[i][(j*V*pow(V,P-i-1) + l + k*pow(V,P-i-1))];
}
}
}
}

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C/C++ :: Checking Array And Generating Unique Numbers

Feb 11, 2014

Here is what I'm trying to accomplish (it is a rather simple program): A classroom of students are to grade a certain number of other exams. The exams should be distributed equally and RANDOMLY, every student should receive the same number of exams, and no student should receive their own exam to grade. The only problem I have is to generate unique random exams for each student. Right now, I have it set to where each exam is distributed the same number of times, every student gets the same number of exams to grade, and no one gets there own. However, I don't have any parameters that prevent one student from getting the same exam multiple time.

Here is an example output:

Student 1 will grade: 4 3 2 5 <- CORRECT OUTPUT (no exam appears more than once)
Student 2 will grade: 5 5 5 1 <- exam 5 appears three times
Student 3 will grade: 4 2 2 2 <- exam 2 appears three times
Student 4 will grade: 3 3 1 1 <- exams 3 and 1 each appear twice
Student 5 will grade: 1 3 4 4 <- exam 4 appears twice
(each exam appears four times and every student is assigned four exams. no one gets their own)

Here is my code (area of problem is close to the bottom):

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
void create_class (int);
int main (void) {
srand(time(NULL));

[Code] ....

I tried keeping the exams for each student in the array exam and then checking each one every time I generate a number, but that didn't work.

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Visual C++ :: Generating Lottery Numbers In Specified Range

Dec 4, 2012

Write a function named generateLotteryNumbers. The function is passed an int array of size 5. The function should generate 5 different lottery numbers in the range 1 to 50 inclusive and place the numbers in the array. The declaration is as follows:

void generateLotteryNumbers (int lotteryNumbers []);

Note that no data is passed in to the function. The array is used to return the function results. Thus the parameter is an OUT parameter. Do not display the result. Return the result.

Do not seed the random number generator inside the function. If you seed the random number generator inside the function and the function is called many times in the same second, your function will return the same results each time it is called.

I know how to generate the numbers in the specified range but I do not know how to test for duplicates. Here is the code I have so far:

Code:
//This program will test the "generateLotteryNumbers" function
#include <iostream>
#include <cstdlib>
#include <ctime>
using namespace std;
void generateLotteryNumbers (int lotteryNumbers[]);

[Code] ....

When I try to compile this, my compiler tells me that lines 41 and 46 require an array or pointer type.

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C++ :: Make 10 Random Numbers Thus Making 10 Random Flips Of Coin?

Aug 31, 2013

I want to make 10 random numbers thus making 10 random flips of a coin. I am getting 10 tails or 10 heads!

Code: #include <iostream>
#include <ctime>
#include <cstdlib>
using namespace std;
int main(int argc, const char * argv[])
{

[Code].....

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C++ :: Program Is Not Calculating Sums Correctly?

Jun 20, 2014

I am getting this weird error when calculating sums. Here is what my program does: it generates two random numbers and then randomly puts either an addition or subtraction sign between the two and then I am asked to enter what the correct answer for that question is. But on some of the subtraction questions when I give the answer it says I got it wrong after which the program shows the right answer. What's confusing is that the answer the computer calculates is the same that I entered. Anyways the complete program and a screenshot of the console window which shows the error are below. The function in question here is decAddSub at line 54. The error is shown in the first sum in the output window. It doesn't affect addition problems and only affects some of the subtraction problems.

#include<iostream>
#include<stdlib.h>
#include<time.h>
#include<random>

[Code].....

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C++ :: Adding Sums With Void Functions

May 3, 2013

1) This first function initializes an array of 30 components so that the first 15 components are equal to the square of the index value and the last 15 components are equal to the index value multiplied by 3.

2) The second function processes the array by finding the sum of the first 15 components and the sum of the last 15 components to determine which sum is bigger. The output to the screen should do the following:

a)State “The sum of the first 15 components is:” and then show the sum.
b)State “The sum of the last 15 components is:” and then show the sum.
c)State which of the two resulted in the greater sum or if the two sums were equal.

Function: The program uses two subroutines. One to initialize an array and the other to process the array and print to screen results:

#include <iostream>
#include <iomanip>
// Include any other header files you may need.

const int ARRAY_SIZE = 30;
void initialize ( double list[], int index );
void square ( double list[], int index );
void threeTimes ( double list[], int index );
void output ( const double list[], int index );

[Code] .....

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C/C++ :: 3x3 Magic Square That Sums Up To 15 On All Sides

Mar 10, 2015

I have an assignment that I have to make a 3x3 magic square that sums up to 15 on all sides. I can't use arrays, just Loops and If and Else statements.

My first attempt was like this

//Program for printing magic square that sums up to 15.

#include <iostream>
using namespace std;
int main() {
int a, b, c, d, e, f, g, h, i;
int r1, r2, r3;
int c1, c2, c3;

[Code] .....

I can't think of a way to loop that when it prints out, it will have a sum of 15 on all sides and/or print one of the 8 solution for a 3x3 magic square.

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C/C++ :: Rolling Multiple Dice - Compare Total Sums

Feb 1, 2015

I am building the game risk and I want to start off with a dice rolling mechanism. In risk 5 die are needed so I want to know the most efficient way of churning out the code for this. Since the players have the options of rolling 1, 2 or 3 die (max 3 for attacker, and max 2 for defender) I was thinking something like this after searching the web for a few different options:

const int minNum = 1;
const int maxNum = 6;
int numberGenerator(){
int x;
x = minNum + rand() % (maxNum - minNum + 1);

[Code] ....

Since I will be asking the player the option to choose how many die to roll, is this the most efficient way? I want to compare the total sums after the die are rolled. If they choose 3 dice (the attacker) I will simply call the first 3 methods and either 1 or 2 for the defender.

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C++ :: Random Integers (numbers)

Oct 17, 2014

I'm trying to make a C++ program that generate 6 random numbers ( from 100,000 to 999,999 ), okay, so I wrote a few lines..

Code:
srand(time(0));
for (int i = 0; i < 5; i++)
{
std::cout << 100000 + (rand() % 999999) << std::endl;
}

The problem is, that it generates numbers like this:

117,207
123,303
131,083
... etc etc..

They're all starts with 100K, i want them to be an actual random..

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C++ :: Random Numbers Are Not In Specified Range

Nov 9, 2014

My program behaves weird... I wanted to generate 10 random numbers from 1 to 100 each of them bigger than previous, using the while loop and function that returns a random number in specified range.

When I run the program, I get numbers much bigger than 100, even negative number, and numbers are same every time I run the program.

Code:
#include <ctime>#include <cstdlib>
#include <iostream>
using namespace std;
int range(int low, int high);

[Code] .....

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C :: Generate Random Numbers

Mar 17, 2013

I'm trying to generate random numbers so that I can assign people to teams. So far I have come up with this

Code:

int generateTeam(){
int i, teamNumber, c, n;
for (c = 0; c <= 5; c++) {
n = rand()%100 + 1;
}

[code]....

}//end generateTeam I'm not sure how to make it so that I can exclude the previous random number when generating the next one. As an example, I have 22 students and I get the number 19. Now I can't have 19 again because that guy already has it.

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