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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 used3001765
Undeclared VariablesCompilerErrorUndeclared variable used2322220
Undefined ReferencesLinkerErrorUndefined reference to function or variable2311
Missing Return StatementAnalyzerWarningFunction is missing return statement211053
Missing Array SizeCompilerErrorThe size of an array is not specified181139
Empty BlockAnalyzerWarningYour program features an empty block211264
Single Quote StringCompilerWarningUsing single quote as string delimiter225355
Unexpected Break StatementAnalyzerWarningUnexpected break statement210030
Missing break statementAnalyzerWarningMissing break statement1583
Unreachable StatementsAnalyzerWarningUnreachable statements231765
= vs. ==CompilerWarningAssignment used in Boolean expression4421192
Unary OPs in Larger ExprAnalyzerWarningUnary operators used in larger expression2300186
Bitwise vs. LogicalAnalyzerWarningUse of bitwise binary operator instead of logical operator2101127
Expected SemicolonCompilerErrorExpected semi-colon202134
Dangling PointerAnalyzerWarningDangling pointer223162
Dereferencing NULLAnalyzerWarningDereferencing NULL pointer252526
Dereferencing Incomplete TypesCompilerErrorDereferencing a pointer to an incomplete data type2033187
Multi-free on same memory blockAnalyzerWarningFreeing multiple times the same memory block280131
Memory LeakAnalyzerWarningMemory leak250494
Freeing unallocated pointerAnalyzerWarningFreeing non-allocated memory302266
sizeof on PointerAnalyzerWarningUsing sizeof operator on pointer2312
Uninitialized PointersAnalyzerWarningUnitialized pointer1916
Discarding Ptrs QualifiersCompilerWarningAssignment or cast discards pointers qualifier2311
Unchecked MallocAnalyzerWarningReturn value from malloc or similar function is not checked2501183
Unexpected EOFCompilerErrorUnexpected EOF263331
Unterminated literalCompilerErrorMissing end-delimiter for character or string literal2421244
Useless ValueAnalyzerWarningStatement results in a value which is never used2331196
Void not IgnoredCompilerErrorAttempting to use a void returned value390653
Missing EOF NewlineCompilerWarningMissing newline at end of file1730
Multiple Unary Ops on VariableCompilerWarningUsing multiple unary operators on same variable in a single expression240399
Empty Char LiteralCompilerErrorEmpty character literal233239
Using Uninitialized VariableCompilerWarningVariable not initialized232236
Forward Parameter DeclarationCompilerErrorParameter has a forward-declaration2903528
Unexpected Data TypesCompilerErrorUnexpected multiple data types where one is expected260398
Unexpected Arguments NumberCompilerErrorUnexpected number of arguments211068
Mismatch numbers for args / specifiersCompilerWarningThere is a mismatch between the number of format specifiers used in a printf or scanf, and their arguments1821170
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 argument2622138
Using unknwon struct fieldCompilerErrorUnknown struct field262078
Parameters Storage ClassCompilerErrorStorage class specified for parameter212036
Shadowed IdentifierAnalyzerWarningShadowing variable already in scope202120
Argument ConversionCompilerWarningArguments data type is converted2220196
Modifying ParametersAnalyzerWarningFormal parameters are assigned inside function252048
Assign Integer to PointerCompilerWarningAssigning non-NULL constant to Pointer280199
Mixed Pointers DeclarationsAnalyzerWarningDeclaring variables in one statement with pointer and non-pointer data types2320
Missing Function DeclarationCompilerWarningMissing function declaration1931
Function should not be exportedAnalyzerWarningFunction is not static to its file, yet unused in other files3730438
Off by oneAnalyzerWarningA loop might be off by one in its number of iteration; e.g. start at 0 instead of 1170011
Formatting String MismatchAnalyzerWarningA printf or scanf is using a formatting string with conversion specifiers unrelated to the parameters1701
Assign pointer to integerAnalyzerWarningAssigning memory address to variable expecting integer190046