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Widely-used automated code flaw detection tools often find somewhat-overlapping but quite different sets of code flaws, even just looking at automated static analysis tools (e.g., see SEI technical note, Improving the Automated Detection and Analysis of Secure Coding Violations). Some code analysis frameworks use multiple analysis tools to analyze code for a wider variety of code flaws, however the number of code warnings (many of which are false positives) that must be manually inspected increases accordingly (for more information on this topic, see SEI blogpost Prioritizing Alerts from Static Analysis to Find and Fix Code Flaws).
Human code review is manual (not automated, although automation can help document findings and schedule reviews), but can detect some errors that widely-used automated static and dynamic analysis tools do not check for.
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