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Novice Errors Detection for C Programs

Start using NED now!

By using NED, you certify that you read, understood & agreed to the terms of usage.

Option #1 - Select files to upload

Use the file-browser below to select, one by one, all the .c or .h files in your project. Leave empty browsers if you do not need to analyze this many files. When you use the "Analyze" button, your files will be uploaded & analyzed. A new tab will open in your browser with a full report on possible errors.

Option #2 - Drag and Drop the files to upload

You might alternatively select a bunch of files in your file browser then drag and drop them here...

Drop Files Here to Upload

Option #3 - Upload a zip of your projet

You may alternatively zip your entire project folder then select the resulting zip file to upload

Things to keep in mind

This web app has been developed for Firefox. You may download a portable firefox version if you do not want to fully install it on your system. It should work on other standards-adhering browsing

Keep in mind these are potential errors, things you should take another look at in order to make sure they are not mistakes. Unfortunately, there is so much a program may do to understand another program.

Do not hesitate to drop us feedback, see about details here. If you want to learn a bit more about this project read here

Search through our tutorials

This table lists all our tutorials so you may peruse through them. The number of views for each is also displayed; this is not the number of times the error occured in an uploaded set of files but rather the number of times a user clicked on the messages hyperlinked to this tutorial in order to read it.

Similarly, the usefulness is based on the number of users who clicked yes at the bottom of a tutorial page. The uselessness is based on the number of those who clicked no.

The Freq. value represents how often the errors or warnings which the tutorial explains have been found during uploaded files analysis. It is a good estimate of the frequency of the underlying bugs among all NED users

Do not hesitate to use the mini-survey feature which you will find in the last section of each tutorial page. It helps identify both the tutorials in need of improvement but also those we should use as models.

Name From Type Details Views Useful Useless Freq.
Unused VariablesCompilerWarningVariable declared, maybe even assigned, but never used5800154
Undeclared VariablesCompilerErrorUndeclared variable used610083
Undefined ReferencesLinkerErrorUndefined reference to function or variable2800
Missing Return StatementAnalyzerWarningFunction is missing return statement490012
Missing Array SizeCompilerErrorThe size of an array is not specified27003
Empty BlockAnalyzerWarningYour program features an empty block38009
Single Quote StringCompilerWarningUsing single quote as string delimiter23003
Unexpected Break StatementAnalyzerWarningUnexpected break statement23003
Missing break statementAnalyzerWarningMissing break statement3200
Unreachable StatementsAnalyzerWarningUnreachable statements22009
= vs. ==CompilerWarningAssignment used in Boolean expression790087
Unary OPs in Larger ExprAnalyzerWarningUnary operators used in larger expression380016
Bitwise vs. LogicalAnalyzerWarningUse of bitwise binary operator instead of logical operator260017
Expected SemicolonCompilerErrorExpected semi-colon74003
Dangling PointerAnalyzerWarningDangling pointer31004
Dereferencing NULLAnalyzerWarningDereferencing NULL pointer39002
Dereferencing Incomplete TypesCompilerErrorDereferencing a pointer to an incomplete data type250042
Multi-free on same memory blockAnalyzerWarningFreeing multiple times the same memory block24002
Memory LeakAnalyzerWarningMemory leak330049
Freeing unallocated pointerAnalyzerWarningFreeing non-allocated memory39003
sizeof on PointerAnalyzerWarningUsing sizeof operator on pointer2300
Uninitialized PointersAnalyzerWarningUnitialized pointer2200
Discarding Ptrs QualifiersCompilerWarningAssignment or cast discards pointers qualifier2300
Unchecked MallocAnalyzerWarningReturn value from malloc or similar function is not checked340017
Unexpected EOFCompilerErrorUnexpected EOF880013
Unterminated literalCompilerErrorMissing end-delimiter for character or string literal320029
Useless ValueAnalyzerWarningStatement results in a value which is never used2500116
Void not IgnoredCompilerErrorAttempting to use a void returned value23002
Missing EOF NewlineCompilerWarningMissing newline at end of file2100
Multiple Unary Ops on VariableCompilerWarningUsing multiple unary operators on same variable in a single expression27006
Empty Char LiteralCompilerErrorEmpty character literal26002
Using Uninitialized VariableCompilerWarningVariable not initialized360014
Forward Parameter DeclarationCompilerErrorParameter has a forward-declaration23006
Unexpected Data TypesCompilerErrorUnexpected multiple data types where one is expected26006
Unexpected Arguments NumberCompilerErrorUnexpected number of arguments340011
Mismatch numbers for args / specifiersCompilerWarningThere is a mismatch between the number of format specifiers used in a printf or scanf, and their arguments220013
Mismatch types for args / specifiersCompilerWarningThere is a mismatch between the data type of format specifiers used in a printf or scanf, and the data type of the corresponding argument420035
Using unknwon struct fieldCompilerErrorUnknown struct field21006
Parameters Storage ClassCompilerErrorStorage class specified for parameter23003
Shadowed IdentifierAnalyzerWarningShadowing variable already in scope21004
Argument ConversionCompilerWarningArguments data type is converted16100144
Modifying ParametersAnalyzerWarningFormal parameters are assigned inside function85009
Assign Integer to PointerCompilerWarningAssigning non-NULL constant to Pointer25008
Mixed Pointers DeclarationsAnalyzerWarningDeclaring variables in one statement with pointer and non-pointer data types2200
Missing Function DeclarationCompilerWarningMissing function declaration8100
Function should not be exportedAnalyzerWarningFunction is not static to its file, yet unused in other files210071
Off by oneAnalyzerWarningA loop might be off by one in its number of iteration; e.g. start at 0 instead of 129003
Formatting String MismatchAnalyzerWarningA printf or scanf is using a formatting string with conversion specifiers unrelated to the parameters2100
Assign pointer to integerAnalyzerWarningAssigning memory address to variable expecting integer23006