Why doesn't this Pascal's Triangle program work?

Question

Row is user-inputted.

cout << "Input the number of rows: ";
cin >> row;
column=row;

int triangle[row][column];

for (i=0;i<=row;i++){
    for (j=0;j<=column;j++){
           triangle[i][j]=0;
    }
}

for (i=0;i<=row;i++){
    for (j=0;j<=i;j++){
           if (j==0 || j==i){
           triangle[i][j]=1;
           } else {
           triangle[i][j]=triangle[i-1][j]+triangle[i-1][j-1];
           }
    }
}

cout << "Pascals triangle with " << row << " rows.";

for (i=0;i<=row;i++){
    for (j=0;j<=i;j++){
        cout << triangle[i][j] << "\t";
    }
    cout << endl;
}

It does give out proper results when the row is seven, but it somehow crashes when the inputted row is greater than 8.

Please show the rest of the code. In particular the declaration of `triangle`. — David Heffernan, Feb 09 '13 at 15:49

score 2 · Accepted Answer · answered Feb 09 '13 at 15:52

2

Most likely triangle is not declared with enough memory for the indices you use. If row==column==8 then you need to declare it like this:

double triangle[9][9];

Because C++ uses zero-based indices this allows for indices in the range 0 to 8 inclusive. Most likely your declaration is like this:

double triangle[8][8];

answered Feb 09 '13 at 15:52

David Heffernan

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Wew. Thanks. I forgot about that one. Sorry, newbie here. – user2027369 Feb 09 '13 at 15:56
If the answer is correct you should accept it – phuclv Dec 19 '13 at 00:27

Why doesn't this Pascal's Triangle program work?

1 Answers1