When implementing algorithms that involve spacing, gaps, or iterative calculations, carefully verify loop bounds and edge cases to prevent off-by-one errors. These errors commonly occur when calculating spacing between N items (which requires N-1 gaps, not N gaps) or when applying operations to boundary elements.
Key areas to scrutinize:
Example from gap calculation:
// Wrong: adds gap for all children (N gaps for N items)
for (int i = 0; i < childCount; i++) {
mainDim += childSize + betweenMainDim;
}
// Correct: adds gap only between children (N-1 gaps for N items)
const bool isLastChild = i == childCount - 1;
if (isLastChild) {
betweenMainDim -= gap; // Remove gap for last item
}
Always validate your algorithm with boundary cases: single item, empty collection, and maximum expected size. Consider whether conditional checks like if (lineCount > 1)
are truly necessary or artifacts of avoiding edge case bugs.
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