victor - 1 year ago 194

C++ Question

I'm still very new to C++, and seem to have an issue. When I run my program, my

`getInt()`

`myInteger`

`print()`

`print()`

`myInteger`

`getInt()`

`#include <iostream>`

#include <iomanip>

#include <cstdlib>

#include <cmath>

using namespace std;

class myInt {

public:

myInt();

myInt(int newInt);

void print();

void setInt(int);

int getInt();

int sumDigits();

int reverse();

int oddDigitCount();

int evenDigitCount();

int zeroCount();

private:

int myInteger;

};

int main()

{

srand(815);

myInt theNum;

for (int i = 0; i != 10; i++) {

theNum.setInt(rand());

theNum.print();

}

return 0;

}

myInt::myInt()

{

myInteger = 0;

}

myInt::myInt(int newInt)

{

setInt(newInt);

}

void myInt::setInt(int newInt)

{

if (newInt > 0)

myInteger = newInt;

else

myInteger = abs(newInt);

}

int myInt::getInt()

{

return myInteger;

}

int myInt::sumDigits()

{

int sum = 0, rem;

while (myInteger != 0) {

rem = myInteger % 10;

sum += rem;

myInteger /= 10;

}

return sum;

}

int myInt::reverse()

{

int reversed = 0;

int quo, rem;

quo = myInteger;

while (quo != 0)

{

rem = quo % 10;

reversed = reversed * 10 + rem;

quo /= 10;

}

return reversed;

}

int myInt::oddDigitCount()

{

return 0;

}

int myInt::evenDigitCount()

{

return 0;

}

int myInt::zeroCount()

{

return 0;

}

void myInt::print()

{

cout << "The number is " << getInt() << endl

<< "----------------------------------------" << endl

<< "Adding the digits result" << setw(16) << sumDigits() << endl

<< "Reversing the digits result" << setw(13) << reverse() << endl

<< "Odd digits" << setw(30) << oddDigitCount() << endl

<< "Even digits" << setw(29) << evenDigitCount() << endl

<< "Zeros" << setw(35) << zeroCount() << endl

<< endl;

}

Output for first two iterations of for loop,

The number is 0

Adding the digits result 9

Reversing the digits result 72

Odd digits 0

Even digits 0

Zeros 0

The number is 0

Adding the digits result 20

Reversing the digits result 41681

Odd digits 0

Even digits 0

Zeros 0

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Answer Source

```
int myInt::sumDigits()
{
int sum = 0, rem;
while (myInteger != 0) {
rem = myInteger % 10;
sum += rem;
myInteger /= 10; // <-- HERE
}
return sum;
}
```

This code resets `myInteger`

back to 0 before you print it.

You call it as part of this statement:

```
cout << "The number is " << getInt() << endl
<< "----------------------------------------" << endl
<< "Adding the digits result" << setw(16) << sumDigits() << endl
<< ...
```

The compiler apparently has chosen to evaluate the call to `sumDigits`

before the call to `getInt`

(C++ leaves this order unspecified), so by the time `getInt`

looks at `myInteger`

, it's already been set to 0 by `sumDigits`

.

To fix this, do the same thing you do in `reverse`

: Create a local variable (such as `quo`

), which you can modify without affecting anything else.