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# Prime numbers using functions. Writing 1-100 prime numbers to a file? Need help with programming assignment

25 Answers

0

woah man I'm not looking for someone to do my homework....im frustrated because I can't figure it out.

0

I was trying to do it for 8 hours yesterday.

0

And again, you didn't ask a question, or specified the language
Post the lines of code you made in 8 hours yesterday

0

#include<iostream>
using namespace std;
bool isPrime(int, int);
int main() {
int number;
int number2 = 1;
cout << "Please enter a number between 1 and 100.\n\n";
cin >> number;
isPrime(number, number2);
if (isPrime(number, number2)==true) {
cout << number << " is a prime number.";
}
else cout << number << " The number is not a prime number.";
system("pause");
}
bool isPrime(int number, int number2){
bool status;
if (number % number2 == 0) {
status = true;
}
else if (number % number2 > 0) {
status = false;
}
return status;
}

0

Like I said I'm not trying to get someone to do my homework..im at a frustrated level and my school doesn't offer any help...

0

and I'm trying to learn coding. I'm not trying to get someone to do it for me

0

Your program ask for a number from 1-100 and then you check if it is prime
And I think it is wrong
I think they are requesting you a program that prints ALL the prime numbers from 1 to 100
And you are printing in terminal, and you need to print the numbers in a file

0

A prime number is a number that is only evenly divisible by itself and 1. For example, the number 5 is prime because it can only be evenly divided by 1 and 5. The number 6, however, is not prime because it can be divided evenly by 1, 2, 3, and 6.
Write a function name isPrime , which takes an integer as an argument and returns true if the argument is a prime number, or false otherwise. Use the isPrime function in a program that stores a list of all the prime numbers from 1 through 100 in a file named allprimes.dat.
TIP: Recall that the % operator divides one number by another, and returns the remainder of the division. In an expression such as num1 % num2 , the % operator will return 0 if num1 is evenly divisible by num2 .

0

with mine its returning every number the user types in as true for a prime number..

0

That's because you declared variable number2 is equal to 1
And any number divided by 1, gives you a reminder of 0
You only need one parameter in your function isPrime

0

oh duh....but if I put number%1 !=0 it gives me an error

0

why would u use a decrement instead of an increment?

0

#include<iostream>
using namespace std;
bool isPrime(int, int);
int main() {
int number;
int number2 = 1;
cout << "Please enter a number between 1 and 100.\n\n";
cin >> number;
isPrime(number, number2);
if (isPrime(number, number2)==true) {
cout << number << " is a prime number.";
}
else cout << number << " The number is not a prime number.";
system("pause");
}
bool isPrime(int number, int number2) {
bool status;
//this is what I changed. why wouldn't it work?
for (number = number2; number2 = number2++;) {
}
if (number % number2 == 0) {
status = true;
}
else if (number % number2 != 0) {
status = false;
}
return status;
}

0

#include<iostream>
using namespace std;
bool isPrime(int, int);
int main() {
int number;
int number2 = 1;
cout << "Please enter a number between 1 and 100.\n\n";
cin >> number;
isPrime(number, number2);
if (isPrime(number, number2)==true) {
cout << number << " is a prime number.";
}
else cout << number << " The number is not a prime number.";
system("pause");
}
bool isPrime(int number, int number2) {
bool status;
for (number = number2; number2 = number2++;) {
if (number % number2 == 0) {
status = true;
}
else if (number % number2 != 0) {
status = false;
}
}
return status;
}
// I mean all of this...it stops after you input the number

0

That's because your function is declared in the top with one parameter, but after you request the number, that function is expecting 2 parameters
You have to modify your function,
isPrime(number)
The for loop and if needs to be equal to ones I posted

0

it has two parameters in the function, both are int

0

Only one is needed
And you are only asking for one to user

0

#include<iostream>
using namespace std;
bool isPrime(int);
int main() {
int number;
cout << "Please enter a number between 1 and 100.\n\n";
cin >> number;
isPrime(number);
if (isPrime(number)==true) {
cout << number << " is a prime number.\n\n";
}
else cout << number << " The number is not a prime number.\n\n";
while (number > 0) {
cout << "Please enter a number between 1 and 100.\n\n";
cin >> number;
isPrime(number);
if (isPrime(number) == true) {
cout << number << " is a prime number.\n\n";
}
else cout << number << "is not a prime number.\n\n";
}
system("pause");
}

0

its still not working properly.. I put in a while loop

0

All wrong