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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 used3401784
Undeclared VariablesCompilerErrorUndeclared variable used2622225
Undefined ReferencesLinkerErrorUndefined reference to function or variable2611
Missing Return StatementAnalyzerWarningFunction is missing return statement241057
Missing Array SizeCompilerErrorThe size of an array is not specified211141
Empty BlockAnalyzerWarningYour program features an empty block231264
Single Quote StringCompilerWarningUsing single quote as string delimiter245356
Unexpected Break StatementAnalyzerWarningUnexpected break statement240031
Missing break statementAnalyzerWarningMissing break statement1783
Unreachable StatementsAnalyzerWarningUnreachable statements261767
= vs. ==CompilerWarningAssignment used in Boolean expression5321207
Unary OPs in Larger ExprAnalyzerWarningUnary operators used in larger expression2600192
Bitwise vs. LogicalAnalyzerWarningUse of bitwise binary operator instead of logical operator2401131
Expected SemicolonCompilerErrorExpected semi-colon232136
Dangling PointerAnalyzerWarningDangling pointer243163
Dereferencing NULLAnalyzerWarningDereferencing NULL pointer282528
Dereferencing Incomplete TypesCompilerErrorDereferencing a pointer to an incomplete data type2333283
Multi-free on same memory blockAnalyzerWarningFreeing multiple times the same memory block300131
Memory LeakAnalyzerWarningMemory leak280495
Freeing unallocated pointerAnalyzerWarningFreeing non-allocated memory352292
sizeof on PointerAnalyzerWarningUsing sizeof operator on pointer2512
Uninitialized PointersAnalyzerWarningUnitialized pointer2116
Discarding Ptrs QualifiersCompilerWarningAssignment or cast discards pointers qualifier2511
Unchecked MallocAnalyzerWarningReturn value from malloc or similar function is not checked2801188
Unexpected EOFCompilerErrorUnexpected EOF283331
Unterminated literalCompilerErrorMissing end-delimiter for character or string literal2621244
Useless ValueAnalyzerWarningStatement results in a value which is never used2631369
Void not IgnoredCompilerErrorAttempting to use a void returned value450655
Missing EOF NewlineCompilerWarningMissing newline at end of file1930
Multiple Unary Ops on VariableCompilerWarningUsing multiple unary operators on same variable in a single expression2703102
Empty Char LiteralCompilerErrorEmpty character literal253239
Using Uninitialized VariableCompilerWarningVariable not initialized262237
Forward Parameter DeclarationCompilerErrorParameter has a forward-declaration33031008
Unexpected Data TypesCompilerErrorUnexpected multiple data types where one is expected2903101
Unexpected Arguments NumberCompilerErrorUnexpected number of arguments241070
Mismatch numbers for args / specifiersCompilerWarningThere is a mismatch between the number of format specifiers used in a printf or scanf, and their arguments2021170
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 argument3022310
Using unknwon struct fieldCompilerErrorUnknown struct field282078
Parameters Storage ClassCompilerErrorStorage class specified for parameter232036
Shadowed IdentifierAnalyzerWarningShadowing variable already in scope222120
Argument ConversionCompilerWarningArguments data type is converted2520200
Modifying ParametersAnalyzerWarningFormal parameters are assigned inside function272048
Assign Integer to PointerCompilerWarningAssigning non-NULL constant to Pointer3001100
Mixed Pointers DeclarationsAnalyzerWarningDeclaring variables in one statement with pointer and non-pointer data types2520
Missing Function DeclarationCompilerWarningMissing function declaration2231
Function should not be exportedAnalyzerWarningFunction is not static to its file, yet unused in other files4330453
Off by oneAnalyzerWarningA loop might be off by one in its number of iteration; e.g. start at 0 instead of 1190011
Formatting String MismatchAnalyzerWarningA printf or scanf is using a formatting string with conversion specifiers unrelated to the parameters1901
Assign pointer to integerAnalyzerWarningAssigning memory address to variable expecting integer220048