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Novice Errors Detection for C Programs

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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 used3801803
Undeclared VariablesCompilerErrorUndeclared variable used3122230
Undefined ReferencesLinkerErrorUndefined reference to function or variable3111
Missing Return StatementAnalyzerWarningFunction is missing return statement291059
Missing Array SizeCompilerErrorThe size of an array is not specified261142
Empty BlockAnalyzerWarningYour program features an empty block291295
Single Quote StringCompilerWarningUsing single quote as string delimiter295357
Unexpected Break StatementAnalyzerWarningUnexpected break statement280032
Missing break statementAnalyzerWarningMissing break statement2183
Unreachable StatementsAnalyzerWarningUnreachable statements301769
= vs. ==CompilerWarningAssignment used in Boolean expression6121216
Unary OPs in Larger ExprAnalyzerWarningUnary operators used in larger expression3000198
Bitwise vs. LogicalAnalyzerWarningUse of bitwise binary operator instead of logical operator2801135
Expected SemicolonCompilerErrorExpected semi-colon272137
Dangling PointerAnalyzerWarningDangling pointer273166
Dereferencing NULLAnalyzerWarningDereferencing NULL pointer322529
Dereferencing Incomplete TypesCompilerErrorDereferencing a pointer to an incomplete data type2733375
Multi-free on same memory blockAnalyzerWarningFreeing multiple times the same memory block330132
Memory LeakAnalyzerWarningMemory leak320499
Freeing unallocated pointerAnalyzerWarningFreeing non-allocated memory3822115
sizeof on PointerAnalyzerWarningUsing sizeof operator on pointer2912
Uninitialized PointersAnalyzerWarningUnitialized pointer2416
Discarding Ptrs QualifiersCompilerWarningAssignment or cast discards pointers qualifier2911
Unchecked MallocAnalyzerWarningReturn value from malloc or similar function is not checked3101196
Unexpected EOFCompilerErrorUnexpected EOF313332
Unterminated literalCompilerErrorMissing end-delimiter for character or string literal3021248
Useless ValueAnalyzerWarningStatement results in a value which is never used2931576
Void not IgnoredCompilerErrorAttempting to use a void returned value490656
Missing EOF NewlineCompilerWarningMissing newline at end of file2230
Multiple Unary Ops on VariableCompilerWarningUsing multiple unary operators on same variable in a single expression3003105
Empty Char LiteralCompilerErrorEmpty character literal283240
Using Uninitialized VariableCompilerWarningVariable not initialized292238
Forward Parameter DeclarationCompilerErrorParameter has a forward-declaration37031494
Unexpected Data TypesCompilerErrorUnexpected multiple data types where one is expected3303104
Unexpected Arguments NumberCompilerErrorUnexpected number of arguments271072
Mismatch numbers for args / specifiersCompilerWarningThere is a mismatch between the number of format specifiers used in a printf or scanf, and their arguments2421174
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 argument3422516
Using unknwon struct fieldCompilerErrorUnknown struct field322080
Parameters Storage ClassCompilerErrorStorage class specified for parameter262037
Shadowed IdentifierAnalyzerWarningShadowing variable already in scope252121
Argument ConversionCompilerWarningArguments data type is converted2820205
Modifying ParametersAnalyzerWarningFormal parameters are assigned inside function302050
Assign Integer to PointerCompilerWarningAssigning non-NULL constant to Pointer3401102
Mixed Pointers DeclarationsAnalyzerWarningDeclaring variables in one statement with pointer and non-pointer data types2820
Missing Function DeclarationCompilerWarningMissing function declaration2531
Function should not be exportedAnalyzerWarningFunction is not static to its file, yet unused in other files4630467
Off by oneAnalyzerWarningA loop might be off by one in its number of iteration; e.g. start at 0 instead of 1220012
Formatting String MismatchAnalyzerWarningA printf or scanf is using a formatting string with conversion specifiers unrelated to the parameters2301
Assign pointer to integerAnalyzerWarningAssigning memory address to variable expecting integer250050