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Calling Fuctions C++

 
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Calling Fuctions C++
SoChrisP
post 5 Oct, 2008 - 05:00 AM
Post #1


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Joined: 1 Oct, 2008
Posts: 6
Question Details:
I need help with this question in Microsoft Visual Studios 2008 C++ !!

1) isPrime:
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 a prime because it can be divied 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. Demostrate the functions in a complete program.

Tip: Recall that the % operator divides one number by another, and returns the remainder of the divison. In an ecpression such as num1% num2%, the % operator will return 0 if num1 is evenly divisible by num2.


So Far I have this, but there are syntex errors that i can not solve.

cpp
#include <iostream>
using namespace std;

bool isPrime(int prime)

{
                cout << "Enter in an integer";
	cin >> prime;
	
   for (int counter = 2; counter < prime; counter++)
	{
      if(prime%counter == 0)

	{
        return false;
	}
	}

    system ("pause");
    return true;
}

MOD EDIT: Please code.gif
Thanks, gabehabe smile.gif
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gabehabe
post 5 Oct, 2008 - 05:07 AM
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My Contributions
Try my snippet: http://www.dreamincode.net/code/snippet2196.htm

Hope this helps smile.gif

EDIT: Aside from that, I'll quickly explain what's wrong with your code~

You don't have a main function. All programs require a main function: It is the entry point to the program.

A design tip:
When writing function such as this, I tend to avoid input/output in the function. Try to keep it basic, and automated~ that way, the user doesn't do anything in the function.

Then, you can call it like this:
cpp
int main()
{
    cout << "Enter a number: ";
    int num;
    cin >> num;
    if (isPrime(num))
        cout << num << " is prime! w00t!";
    else cout << num << " is not prime. gosh darn it!";
    cin.get(); // pause for input (try to avoid system())
    return EXIT_SUCCESS; // successful execution
}
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SoChrisP
post 5 Oct, 2008 - 05:20 AM
Post #3


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Joined: 1 Oct, 2008
Posts: 6
Thax this helps a lot. I completly forgot about the int main haha. But, i still have one problem wrong with the code. When i run the program i have a syntax error that says "isPrime idenitfer not found". Does this mean that I havent declared isPrime variable?
thax


_______________________________________________________________________________
QUOTE(gabehabe @ 5 Oct, 2008 - 06:07 AM) *

Try my snippet: http://www.dreamincode.net/code/snippet2196.htm

Hope this helps smile.gif

EDIT: Aside from that, I'll quickly explain what's wrong with your code~

You don't have a main function. All programs require a main function: It is the entry point to the program.

A design tip:
When writing function such as this, I tend to avoid input/output in the function. Try to keep it basic, and automated~ that way, the user doesn't do anything in the function.

Then, you can call it like this:
cpp
int main()
{
    cout << "Enter a number: ";
    int num;
    cin >> num;
    if (isPrime(num))
        cout << num << " is prime! w00t!";
    else cout << num << " is not prime. gosh darn it!";
    cin.get(); // pause for input (try to avoid system())
    return EXIT_SUCCESS; // successful execution
}
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gabehabe
post 5 Oct, 2008 - 06:04 AM
Post #4


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Posts: 5,402



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My Contributions
Post your code exactly as it is. It sounds like you've missed your function prototype:

cpp
#include <stuff>
using stuff;

void doStuff(int a); // prototype

int main ()
{
    doStuff(5);
    cin.get();
    return EXIT_SUCCESS;
}

// function definition:
void doStuff(int a)
{
    // do stuff here
}


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