Nassi-Shneiderman structogram: the full guide
A structogram (Nassi-Shneiderman diagram, NSD) shows an algorithm as nested boxes with no arrows. The whole logic reads top to bottom as a single block, which is why it is often required as an alternative to a flowchart. Below: every block shown visually, a live example, and how to build one from code in seconds.
The three building blocks
Any algorithm is these three, nested inside one another. No arrows — nesting shows the control flow directly.
Actions one after another — a stack of boxes, top to bottom.
A condition splits into two columns, “Yes” on the left and “No” on the right.
A frame wraps the repeated body on the top and left side.
A live example
Grading a score — a branch nested after an input. This is exactly what rombik outputs from code.
Structogram vs flowchart
Same logic, two views. A structogram is more compact and arrow-free; a flowchart is more familiar to graders. rombik builds both from the same code — flip one toggle.
Flowchart per ISO 5807 — the full guide →Make a structogram from code
Paste code in any of 10 languages, flip the “Structogram” toggle, and export to Word, Visio, draw.io, Typst, Excalidraw, SVG, PNG or PDF as native objects.