Hello, I need help with a C++ program.

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I need to write a program, Whose output should be like, every first element of an array is 1 and every second element is 0. I need to check in the array if the element is odd then print out 1 and if the element is odd then print out 0. I need to check this condition in if condition.Just like Finite state machine. I am failing in doing so. Any help would be appreciated.

What I have tried:

using namespace std;

int main(){
	
	cout<<"Enter the size of array"<<"\n";
	
	int n,i;
	cin>>n;
	int array[n];
	for( i=0; i<n;i++){
	if(array[i] % 2!=0 && array[i] % 2==0){
		
	}
	cout<<"1,0";
			
}

}

Posted 27-May-18 4:35am

Nabeel Munir

Updated 27-May-18 6:46am

User 7429338

v2

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[no name] 27-May-18 10:45am

a.) if(array[i] % 2!=0 && array[i] % 2==0) in words:
if value is odd and value is even

b.) Quote: "I need to check in the array if the element is odd then print out 1 and if the element is odd then print out 0"

Richard MacCutchan 27-May-18 11:09am

Your main problem is that you never enter any values into the array.

[no name] 27-May-18 11:16am

A very good Point which I missed :-O

Nabeel Munir 27-May-18 11:37am

Hello, Could you please be a little more specific?

After trying the code below:
for(i= 0; i < n; i++)
{
if(array[i] % 2 !=0 || array[i] % 2 ==0){
cout<<"1,0,";
}
}
when i execute the code, For example user enters size of array = 4, The output it gives is, 1,0,1,0,1,0,1,0... Which is still not correct. what i need is, If user enters Value 4, The output should be: 1,0,1,0. every odd should be 1, every even should be 0.

[no name] 27-May-18 11:41am

"every odd should be 1, every even should be 0."
Array Index or Array Content?

What is this now if(array[i] % 2 !=0 || array[i] % 2 ==0)?
It will be always true....

Either a number is odd or even. To check for even (value % 2) == 0 is enough. And if the result of this check is false you know the number is odd....

Richard MacCutchan 27-May-18 12:39pm

You have created an array of 'n' elements but you never put any values into it. So whatever results you get are meaningless. Once you have the array you should fill it up with the numbers 1 to n. And your if test is still wrong. You only need to test for one condition, either odd or even, not for both.

Try writing out the specification and the steps required for your program first. You can then use that information to construct your code in a simple logical fashion.

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User 11060979 · Accepted Answer · 2018-05-27T05:03:00

Solution 1

See also my comments. Assuming you Need to print "1" for odd numbers and "0" for even number you don't even Need an if.

This because
1 % 2 results in 1
2 % 2 results in 0
3 % 2 results in 1
4 % 2 results in 0
... and so on. Consult e.g. wiki for detailed Information about the Modulo Operator.

Version I Check Array values
Now I'm not familar with cout but something like this should do the job:

C++

for(i= 0; i < n; i++)
{
   cout << array[i] % 2;
}

[Edit0]
Version II Check index

C++

for(i= 0; i < n; i++)
{
   cout << i % 2;
}

[Edit1]
Version III Check index'

C++

for(i= 0; i < n; i++)
{
   cout << (i + 1) % 2;
}

Note: Keep in mind the comment of Richard MacCutchan - Professional Profile[^] : "Your main problem is that you never enter any values into the array."

Posted 27-May-18 5:03am

User 11060979

Updated 27-May-18 6:05am

v5

Comments

Nabeel Munir 27-May-18 11:46am

@0x01AA,Could you please be a little more specific? I need code to go through every index in the array and check if the index is odd it should print 1 and if even it should print 0. if I go for cout << array[i] % 2; that you have suggested, and execute the program and enter for example array size: 4, the output it gives is: 0010.
And what do you mean by,Your main problem is that you never enter any values into the array."

[no name] 27-May-18 11:50am

See Version II in updated answer. For this case to Array itself is useless which Looks odd (in other words 1%2) to me :-)

Nabeel Munir 27-May-18 12:02pm

It works, but it is giving the opposite result, Like: 0 1 0 1. I need 1 0 1 0.

[no name] 27-May-18 12:05pm

See Version III and ___please____ try to understand it an not just copy it!! ;)

Nabeel Munir 27-May-18 12:06pm

Yeah that is what i want to do, I want to understand how it works. That is why i also need some explanation.

[no name] 27-May-18 12:07pm

Now it is your choice to accept the answer or not ;)

Nabeel Munir 27-May-18 12:09pm

I accept your answer, But i really want to understand how it works.

[no name] 27-May-18 12:12pm

Thank you. See comment below.

Nabeel Munir 27-May-18 12:08pm

It works, but, How, Could you please explain? i is index of array and % 2 i understand but what + 1 does, does it check the next index?

[no name] 27-May-18 12:12pm

No it does not check the next index. It is simply a Special case for x % 2 to invert the result. To really understand this you Need first to be comfortable with Modulo Operator. Do you understand Modulo opreator? Can you describe what Modulo Operation means?

Nabeel Munir 27-May-18 12:15pm

Yeah i know what modulo (%) does. It returns the remainder after division of two numbers.

[no name] 27-May-18 12:33pm

Then it should also easy for you why x % 2 and (x+1) % 2 does "invert" the result. Take a sheet of paper and note x= 0...5 and as a second row also x+1. On the third row note x%2 on the 4'th (x+1)%2. Keep in mind x%2 is a Special case raleted to "invert" the result. Do the same with e.g. x%3 and (x+1)%3. This does not invert the result, but it gives something like a "delay"/"shift"/"Offset"....

To be honest, as a non native english Speaker, I have some Problems to explain all this intuitiv, sorry about that :(

Richard MacCutchan 27-May-18 12:40pm

None of this matters until the array actually gets initialised with some valid data.

[no name] 27-May-18 12:44pm

If you really read through all comments, at the end OP was interested only in the index. The Array values - more even the Array - was out of question and I don't see/understand why this Array was ever mentioned....

Richard MacCutchan 27-May-18 12:49pm

It was mentioned because it is the most important part of the program. Using a block of memory without putting any values in it is just a waste of time.

Nabeel Munir 27-May-18 12:44pm

Hello sir, Could you please be a little more specific?

Richard MacCutchan 27-May-18 12:50pm

I have been very specific, go and look at my latest comment to your question above.

Nabeel Munir 27-May-18 12:53pm

Ohh. i get now what You mean, I did what u told to do. I get it now. thank you so much sir. :)

KarstenK · Accepted Answer · 2018-05-27T06:48:00

Solution 2

When you want to enter the array size you need to allocate dynamic memory.

C++

int *array = new int[n];
//work it 
delete array;

And you need a loop to fill the array.

Tip: use braces in your operations for clarity and avoiding bugs.

Posted 27-May-18 6:48am

KarstenK