Skip to content
Free public beta until December 4, 2026: every course is open, no card needed. After that, the first chapter of each course stays free and full access is a one-time $39 ($19 for up to 100 founding members chosen for helpful feedback). Your progress is kept. How the beta works

null-state analysis

The compiler tracking whether each reference might be null at each point.

Flow analysis assigns each reference expression a null state (not-null or maybe-null) and warns on dereferences and assignments that may be null.

Examples

  • After if (name is null) return;, the compiler knows name isn't null, so name.Length gets no warning.

See also

nullable annotation null-forgiving operator warning
Read the full section →