Four sides of square: Difference between revisions

</pre>

=={{header|C++}}==

<lang cpp>#include <concepts>

#include <iostream>

// Print each element of a matrix according to a predicate. It

// will print a '1' if the predicate function is true, otherwise '0'.

void PrintMatrix(std::predicate<int, int, int> auto f, int size)

{

for(int y = 0; y < size; y++)

{

for(int x = 0; x < size; x++)

{

std::cout << " " << f(x, y, size);

}

std::cout << "\n";

}

std::cout << "\n";

}

int main()

{

// a lambda to show the sides

auto fourSides = [](int x, int y, int size)

{

return x == 0 || (y == 0) || (x == size - 1) || (y == size - 1);

};

PrintMatrix(fourSides, 8);

PrintMatrix(fourSides, 9);

}

</lang>

{{out}}

<pre> 1 1 1 1 1 1 1 1

1 0 0 0 0 0 0 1

1 0 0 0 0 0 0 1

1 0 0 0 0 0 0 1

1 0 0 0 0 0 0 1

1 0 0 0 0 0 0 1

1 0 0 0 0 0 0 1

1 1 1 1 1 1 1 1

1 1 1 1 1 1 1 1 1

1 0 0 0 0 0 0 0 1

1 0 0 0 0 0 0 0 1

1 0 0 0 0 0 0 0 1

1 0 0 0 0 0 0 0 1

1 0 0 0 0 0 0 0 1

1 0 0 0 0 0 0 0 1

1 0 0 0 0 0 0 0 1

1 1 1 1 1 1 1 1 1