C++ :: Finding If A Number Is Prime - Large Numbers

Sep 15, 2013

I have a very large number in word ~6million digits long

I wish to make a program to check if it is prime.

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C/C++ :: Finding All Prime Numbers To Nth Prime Number

Aug 24, 2014

I'm a new coder for C++, and I've recently learned java before starting this programming language. I'm attempting to find all prime numbers up to the number a user enters (i.e. User enters 10, System shows "1,2,3,5,7"),

#include <iostream>
#include <cstdlib>
using namespace std;
int main(int argc, char** argv) {
int num;
cout << "Enter a positive number." << endl;

[Code] ....

I've been looking at my forloop, and I can't seem to pinpoint the problem with it.

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C++ :: Finding All Prime Numbers Using Class Number

Feb 20, 2015

Write a program that prompts the user to enter a number larger than 2. The program should use the Number class to determine the prime numbers between 2 and the number entered, and display them in the console window.I've been stuck for a while now and just lost in implementing classes and contstructors.

#include <iostream>
using namespace std;
int main(int argc, char * argv[])
{
cout << "Enter a number larger than 2: " << endl;
int n;
cin >> n;

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C++ :: Prime Number Program Not Working With Odd Non-prime Numbers

Dec 2, 2014

I have a program that gets prime numbers that doesn't work. It looks like it works for all prime numbers except odd non-prime ones. Here is the code:

Code:
#include <iostream>
using namespace std;
bool isPrime(int prime) {
while(true) {
int track = 0;

[Code] ...

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C++ :: Finding Divisers Of Non-prime Numbers?

Mar 17, 2013

I have written a program that finds the divisers of non-prime numbers and outputs them. However, the output is only one diviser per line(because of the repetition to find the divbisers), but the instructor wants us to have 5 to 10 divisers per line. How can i write this loop so it will only output the divisers in one line?

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C++ :: Finding Only Prime Numbers With For Loops

Feb 18, 2013

A prime number is a number greater than 1 which is only evenly divisible by 1 and itself. For this assignment you will find which numbers from 2 to n (where n is a user-specified number) are prime. Ask the user for a number, n, greater than 2. Keep asking for a number until a number greater than 2 is provided. Assume that the user will only enter numbers (that is, you do not need to check if a user enters text).

Use a loop to iterate on a variable, i, from 2 through n. For each iteration, check all numbers from 2 through i to determine whether the number is prime. If it is prime, print out i and the word "Prime". Use the modulus operator, %, to determine if a number is prime

Example output:

Please enter a number larger than two: -939 Please enter a number larger than two: 2 Please enter a number larger than two: 20 2 Prime 3 Prime 5 Prime 7 Prime 11 Prime 13 Prime 17 Prime 19 Prime

This is what I have so far. I suppose i'm not really understanding how to continue with the second for loop. The first one just prints out a list of numbers from 2 to the number designated by the user. In my case that variable is user_input.

Code:
// Alen
// Prime
//

# include <iostream>
using namespace std;

[Code] ....

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C++ :: Finding If A Number Is Prime Or Not

Oct 3, 2013

cin.ignore (10);
return 0;
}

Its not working

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C++ :: Finding If A Number Is Prime?

Oct 3, 2013

We need it to say if the number is prime or not we need the equation for the if statement or if we have something else wrong to let me know.

#include <iostream>
using namespace std;
int main () {
int number;
bool countr;
for (countr = 0; countr <= 2; countr ++)

[Code] ....

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C/C++ :: Finding Prime Factors Of A Number

Mar 18, 2015

I am trying to find the prime factors of a number but when i compile and run my code after i enter a number it just closes it doesn't print ....

included library : [URL] ....

#include "std_lib_facilities.h";
void prime(int n) {
int result;
result = 0;
int i;
for (i = 2; i == n*n; ++i)

[Code] .....

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C++ :: Finding Largest Prime Factor Of A Number?

Mar 10, 2013

I am trying to find the largest prime factor of a number. But when I am trying to determine if a number is a prime number in the function:

int is_prime(int number), I am unable to exit the loop.

Here is the code:

#include<iostream>
using namespace std;
int is_prime(int number) //the problem is in this function {
int num = number;
int factor=0;
do{
num++;
for(int i=1;i<(num+1);i++){

[code].....

So when the program runs, it first divides 20 by 2, to get 10, then divides 10 by 2 to get 5. Since, // condition 1 is not met, it passes 2 to the function int is_prime(int number). The function is able to return 3, but cannot exit the loop when num is 4.

I think the problem lies in the function: int is_prime(int number).

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C++ :: Number Required After Prime Numbers Addition

Apr 24, 2013

I have to write a code in which the addition of prime number gives the number user input..

for example if user enters 10 then

7+3 = 10
2+3+5 = 10

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C :: Calculate Prime Numbers In Range And Return Count Of Prime Numbers

Apr 28, 2013

I wrote a program which sends a starting and ending range to other processes and the processes calculate the prime numbers in that range and return the count of prime numbers to the head process, process 0. But this is not working properly at the moment. I realize I still have to split up the range based on how many processes I have...I still have not figured out how I want to set that up. I

Code:

#include <stdio.h>
#include <stdlib.h>
#include <mpi.h>
int isPrime(int num);
int main(int argc, char **argv){
}

[code]....

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C++ :: Program Which Print Out All Prime Numbers Less Than Or Equal To Given Number

Nov 11, 2013

how to make a programm in native c++ which print out all prime numbers less than or equal to given number????????

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C :: Write A Code To Find All The Prime Numbers Before A User Entered Number

Apr 9, 2014

I am trying to write code to find all the prime numbers before a user entered number. I started with a working program and when I tried to create a function, it got all messed up.

Code:

#include <stdio.h>
int is_prime( int num );
int get_positive_integer(void);
int main( ) {
int upper; /* upper limit to check */
int num; /* current number to check */
int isprime;
/* used to flag if number is prime or not */

[Code]...

It says the error is on line 23

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C++ :: Finding Mode - Number That Occurs Most Often In A Sequence Of Numbers

Dec 9, 2014

I was doing a side project from my textbook about finding the mode, which is the number that occurs most often in a sequence of numbers. I racked my brain on this for an embarrassing amount of time and finally came up with this, which I think works but for some reason I still feel like I'm not done.

#include "stdafx.h"
#include <iostream>
using namespace std;
void mode(int *, int);
void main() {
const int NUMBERS = 15;
int list[NUMBERS] = {99,73,56,14,28,42,93,64,51,26,56,16,38,81,98};
mode(list,NUMBERS);

[Code] ....

Console Output:

Final Mode 56
Press any key to continue . . .

There it is, I would have commented more but I couldnt think of the right words to explain everything.

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C++ :: Array To Template Class - Finding Largest Number From A Group Of Numbers

Sep 26, 2013

I'm trying to make an array that takes a group of numbers and finds the largest number into a template class.

template<class TYPE>
void Integers(TYPE data) {
int integers[] = {4, 25, 32, 85, 150, 12, 98, 200};
int i = 0;
int Max=integers[0];
for (i=1; i < 8; i++) {

[Code] ....

I'm sure I'm going about it all wrong, but I'm not sure as to get it so that it will accept the arrays input.

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C++ :: Finding Char Array In A Large File

Feb 21, 2015

I have a specific byte (that is unsigned char) array, that I need to find in a very big file (2GB or so), currently I'm using:

size_t fsFind(FILE* device, byte* data, size_t size) {
int SIZE = (1024 > size) ? 1024 : size;
byte buffer[SIZE];
int pos = 0;
int loc = ftell(device);

[Code] ....

Which seems to find proper result on first use, but on subsequent searches it seems to find invalid positions, is there something I'm doing wrong, or is there a better way?

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C :: Recursive Function For Finding And Summing Prime Factors?

Mar 6, 2015

main function:

Code:
int main(){
int n, s = 0;
printf("Insert number: "); scanf("%d", &n);
if (n == 0 || n==-1 || n==1){ printf("No prime factors!
"); return 0; }
if (n < -1) { n = - n; printf("Prime factors: -"); }

[Code] ....

Recursive function

Code:
static int i = 2;
int primefactors (int n) {
if (n == 1) return 0;
if (n%i == 0) {
printf("%d ", i);
return i + primefactors(n / i);

[Code] ....

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C++ :: Find Prime Numbers Between Given Pair Of Numbers And Store Them Into Array?

Apr 18, 2014

Find all the prime numbers between a given pair of numbers. Numbers should be read in from an input file called "numbers.txt" and find all the prime numbers between them. Store the prime numbers in an array, then sort the array from greatest to least. Display the array before and after the sort.

I'm stuck on how to put the prime numbers into an array.

The input file has the numbers 1 & 100.

Here's what I have so far.

#include <iostream>
#include <fstream>
using namespace std;
int main() {
ifstream fin;
fin.open("numbers.txt");

[Code] .....

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C :: Program That Allow User To Enter A Number N And Print Nth Prime Number

Nov 3, 2013

I need to write a program that will allow the user to enter a number "n" and the program tell you that the nth prime number is .....

EXAMPLE

user enters 55

printf("The 55th prime number is %i", variable");

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C++ :: Receive Number From User And Output Largest Prime Number

Nov 20, 2014

I am attempting to write code that receives a number from the user and outputs the largest prime number underneath the user's number. There are no errors in my code, but no matter what number is imputed, the program says the largest prime number is 1. I cannot find where the issue is in the code. Here is the code I wrote:

#include <cstdlib>
#include <iostream>
#include <cmath>
using namespace std;
bool isPrime(int num);//function prototype

[Code] ....

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C++ :: Adding Large Numbers?

Apr 5, 2013

I have to make a function that can add two numbers of any size. So far I have:

#include <iostream>
#include <string>
struct number {

[Code]....

why I'm getting a segmentation fault? It's really dense because of all the conversions I had to do.

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C/C++ :: Factorial Of Large Numbers

Jul 29, 2014

I have designed a code and still i dont get the desired output ....

#include <iostream>
using namespace std;
int fact(int,int);
int arr[200]={1};
int main() {
int n,t,len=0,i=0,j,a;
cin>>t;

[Code] ....

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C/C++ :: How To Go About Factoring Large Numbers

May 6, 2014

My code handles smaller numbers well enough, but I need the program to be able at least factor 100!.

#include <stdio.h>
void factorialOutput(unsigned int &n, int fac[]);
unsigned long long factorial(int n);
int main(int argc, const char * argv[]) {
unsigned int t = 0;
int n[101];

[Code] ......

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C :: Finding Written Numbers In A String And Converting Them To Decimal Numbers

Jun 20, 2013

User enters sentence "The Smiths have two daughters, three sons, two cats and one dog." (The numbers may change depending on what the user chooses to enter. He told us the range would be from zero to nine.) and we have to convert the written numbers within the sentence into actual decimal numbers and print out the new sentence. Ex. The Smiths have 2 daughters, 3 sons...etc.

I have written the following bit of code which reads the string and finds all the "written numbers" but I am not sure how to proceed from there. I am stuck on how to print out the new sentence with the converted numbers as my professor mentioned something about creating the new string using dynamic memory allocation.

Code:
#include <stdio.h>#include <string.h>
int main () {
char A[100];
int length = 0;
int i;

[Code] .....

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C/C++ :: Storing Large Number?

Jan 22, 2015

storing int=9000000000; gives me another number. how can i store the value?my bad int number=9000000000;

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