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Question

I have just learnt C++ for a very short time, and in an assignment I am trying to find a particular target in a 2-dimensional array as follows:

bool simsearch(int array[22][22], int target, int n){
    bool result = 0;
    for (int a = 1; a < n + 1; a++){
        for (int b = 1; b < n + 1; b++){
            if (array[a][b] == target)
                result = 1;
                break;
        }
    }
    return result;
}

and use it like:

if(simsearch(substitute, 6, size) == 0){
        cout << "**Warning**" << '\n';
    }

But, the warning output is always there even if the target is in the array. What is the underlying problem in the code?

Thanks!

Answer 1

Indices of arrays start from 0 and if an array has n elements then the highest index is n-1.

Rewrite the function the following way

bool simsearch( const int array[22][22], int target, int n )
{
    bool found = false;

    for ( int i = 0; i < n && !found; i++ )
    {
        for ( int j = 0; j < n && !found; j++ )
        {
            if ( array[i][j] == target ) found = true;
        }
    }

    return found;
}

Or

bool simsearch( const int array[22][22], int target, int n )
{
    bool found = false;

    for ( int i = 0; i < n && !found; i++ )
    {
        int j = 0;

        while ( j < n && array[i][j] != target ) j++;

        found = j != n; 
    }

    return found;
}

I hope that the argument for n is always equal to 22.:)

Another approach is the following

template <typename T, size_t M, size_t N>

bool simsearch( const T ( &a )[M][N], const T &value )
{
    bool found = false;

    for ( size_t i = 0; i < M && !found; i++ )
    {
        size_t j = 0;

        while ( j < N && !( a[i][j] == value ) ) ++j;

        found = j != N;
    }

    return found;
}

Answer 2

bool simsearch(int array[22][22], int target, int n){
    bool result = 0;
    for (int a = 0; a < n ; a++){
        for (int b = 0; b < n; b++){
            if (array[a][b] == target){
                result = 1;
                break;
            }
        }
        if(result) break;
    }
    return result;
}

This should work. Use brackets and conditions properly

Answer 3

There are two things to notice over here:-

for (int a = 1; a < n + 1; a++)

If n represents size here ( which seems from call to this function) then this you need to change. Array of size 10 must be indexed from 0 to 9.

Second thing rather than returning integer

return result;

you can return true OR false.