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Array Algorithm

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Join Date: Oct 2008

Posts: 22

Reputation: Foe89 is an unknown quantity at this point

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Foe89

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Newbie Poster

Array Algorithm

Nov 19th, 2008

I'm really not understanding what's going on with the array in this. Here's the question.

The following code totals the values in each of the two arrays. Will the code print the correct total for both arrays?

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int total = 0;
int count;
 
for (count = 0; count <= 25; count++)
	total += array1[count];
cout << "The total is " << total << endl;
 
for (count = 0; count <= 25; count++)
	total += array2[count];
cout << "The total is " << total << endl;
 
int total = 0;
int count;

for (count = 0; count <= 25; count++)
	total += array1[count];
cout << "The total is " << total << endl;

for (count = 0; count <= 25; count++)
	total += array2[count];
cout << "The total is " << total << endl;

I'm not understanding this at all. Both arrays hold 25 integer elements but they aren't equal to anything, so im just lost here... or maybe it's really simple and I'm thinking too hard about it...

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Join Date: Jun 2008

Posts: 182

Reputation: mrboolf will become famous soon enough

Solved Threads: 18

mrboolf

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Junior Poster

Re: Array Algorithm

Nov 19th, 2008

If both array1 and array2 contain 25 elements then you should write your for loops

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 for (count = 0; count < 25; count++)
 for (count = 0; count < 25; count++)

as arrays of n elements are indexed from 0 to n-1.

Moreover, the second cout will print the sum of all the elements of the second array plus the sum of all the elements of the first array, as long as you don't reset your total variable between the for loops.

EDIT: What do you mean with "they aren't equal to anything" ? Please clarify this.

Last edited by mrboolf; Nov 19th, 2008 at 5:55 pm.

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Join Date: Oct 2008

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Reputation: ddanbe has much to be proud of

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ddanbe

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Re: Array Algorithm

Nov 19th, 2008

Leave out the equal sign in <= !
Else you are counting from 0 to 25 inclusive, which is 26, not 25.

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Danny

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Join Date: Oct 2008

Posts: 22

Reputation: Foe89 is an unknown quantity at this point

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Foe89

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Newbie Poster

Re: Array Algorithm

Nov 19th, 2008

Don't know what I was thinking there. I changed it to just greater than and then inbetween the two for loop I made total = 0 again. Both arrays outputted -20 so that seems to be working properly. So by not initializing total to = 0 again after the first array is finished will cause total to equal whatever it was in the first output which would be -40 which I checked and so the counter in the for loop must be written as < and not <= because the element starts at 0? I'm going to look in my book about the indexing