code to test odd/even

This is a discussion on code to test odd/even within the C++ Programming forums, part of the General Programming Boards category; This should be real easy but I'm not getting it. User is prompted for an integer. I test the integer ...

  1. #1
    False Return hubris's Avatar
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    code to test odd/even

    This should be real easy but I'm not getting it.
    User is prompted for an integer. I test the integer for being equal to zero or int % 1 !=0. Below I test against mod 2 for even/odd.

    First it thinks everything is an odd integer. Second it thinks everything is odd. I thought % just gives you the remainder of the one figure divided by the other. Am I missing something?
    Code:
    #include <iostream>
    #include <iomanip>
    
    
    using namespace std;
    
    int main()
    {
        int num = 0;
        bool isOdd;
        
        
        cout << "Enter an integer (whole number) and I will tell you" << endl;
        cout << "if the number is odd or even:  " << endl;
        
        cin >> num;
        if(num=0 || num % 1 != 0)
        {
                    cout << "Not an integer.  Shutting down." << endl;
                    }
    
        if(num%2!=0)
        {
                    isOdd = true;
                     }
        if(isOdd=true)
        {
                      cout << "Number is Odd." << endl;
                      }
        if(isOdd=false)
        {
                      cout << "Number is even." << endl;
                      }
                     
                      system ("pause");
                      }
    fyi: the only reason for the bool is because I tried the test with just the % and got the same result. Any help?

  2. #2
    Kernel hacker
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    What is the difference between == and = ?

    --
    Mats
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  3. #3
    C++ Witch laserlight's Avatar
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    You made a typographical error: num=0 should be num==0. But since 0 is an integer, your output in that case does not make sense. Also, unless I missed something, num % 1 != 0 is always false.

    A similiar problem with = versus == is repeated later in your program.
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  4. #4
    False Return hubris's Avatar
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    thank you

    will apply changes. However, I'm still confused if a decimal/fraction is divided by one it is still the decimal, thus producing a remainder. This doesn't apply for %? Please clarify. I apreciate it.

  5. #5
    The larch
    Join Date
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    Code:
        cin >> num;
        if(num=0 || num % 1 != 0)
        {
             cout << "Not an integer.  Shutting down." << endl;
        }
    I thought 0 was an integer. Besides 0, num, being an integer variable, can't store anything that isn't an integer. If you want to check that the user indeed typed an integer, you'll need to test the result of the input statement:

    Code:
        if (!(cin >> num) || num == 0)
        {
             cout << "Not an integer.  Shutting down." << endl;
        }
    I might be wrong.

    Thank you, anon. You sure know how to recognize different types of trees from quite a long way away.
    Quoted more than 1000 times (I hope).

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