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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 used2901765
Undeclared VariablesCompilerErrorUndeclared variable used2222220
Undefined ReferencesLinkerErrorUndefined reference to function or variable2211
Missing Return StatementAnalyzerWarningFunction is missing return statement201053
Missing Array SizeCompilerErrorThe size of an array is not specified171139
Empty BlockAnalyzerWarningYour program features an empty block201264
Single Quote StringCompilerWarningUsing single quote as string delimiter215355
Unexpected Break StatementAnalyzerWarningUnexpected break statement200030
Missing break statementAnalyzerWarningMissing break statement1483
Unreachable StatementsAnalyzerWarningUnreachable statements221765
= vs. ==CompilerWarningAssignment used in Boolean expression4321192
Unary OPs in Larger ExprAnalyzerWarningUnary operators used in larger expression2100186
Bitwise vs. LogicalAnalyzerWarningUse of bitwise binary operator instead of logical operator1901127
Expected SemicolonCompilerErrorExpected semi-colon182134
Dangling PointerAnalyzerWarningDangling pointer203162
Dereferencing NULLAnalyzerWarningDereferencing NULL pointer232526
Dereferencing Incomplete TypesCompilerErrorDereferencing a pointer to an incomplete data type1933186
Multi-free on same memory blockAnalyzerWarningFreeing multiple times the same memory block270131
Memory LeakAnalyzerWarningMemory leak240494
Freeing unallocated pointerAnalyzerWarningFreeing non-allocated memory292265
sizeof on PointerAnalyzerWarningUsing sizeof operator on pointer2212
Uninitialized PointersAnalyzerWarningUnitialized pointer1816
Discarding Ptrs QualifiersCompilerWarningAssignment or cast discards pointers qualifier2211
Unchecked MallocAnalyzerWarningReturn value from malloc or similar function is not checked2401183
Unexpected EOFCompilerErrorUnexpected EOF253331
Unterminated literalCompilerErrorMissing end-delimiter for character or string literal2321244
Useless ValueAnalyzerWarningStatement results in a value which is never used2231196
Void not IgnoredCompilerErrorAttempting to use a void returned value380653
Missing EOF NewlineCompilerWarningMissing newline at end of file1630
Multiple Unary Ops on VariableCompilerWarningUsing multiple unary operators on same variable in a single expression230399
Empty Char LiteralCompilerErrorEmpty character literal223239
Using Uninitialized VariableCompilerWarningVariable not initialized222236
Forward Parameter DeclarationCompilerErrorParameter has a forward-declaration2803512
Unexpected Data TypesCompilerErrorUnexpected multiple data types where one is expected250398
Unexpected Arguments NumberCompilerErrorUnexpected number of arguments201068
Mismatch numbers for args / specifiersCompilerWarningThere is a mismatch between the number of format specifiers used in a printf or scanf, and their arguments1721170
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 argument2522138
Using unknwon struct fieldCompilerErrorUnknown struct field252078
Parameters Storage ClassCompilerErrorStorage class specified for parameter202036
Shadowed IdentifierAnalyzerWarningShadowing variable already in scope192120
Argument ConversionCompilerWarningArguments data type is converted2120194
Modifying ParametersAnalyzerWarningFormal parameters are assigned inside function242048
Assign Integer to PointerCompilerWarningAssigning non-NULL constant to Pointer270199
Mixed Pointers DeclarationsAnalyzerWarningDeclaring variables in one statement with pointer and non-pointer data types2220
Missing Function DeclarationCompilerWarningMissing function declaration1831
Function should not be exportedAnalyzerWarningFunction is not static to its file, yet unused in other files3630438
Off by oneAnalyzerWarningA loop might be off by one in its number of iteration; e.g. start at 0 instead of 1160011
Formatting String MismatchAnalyzerWarningA printf or scanf is using a formatting string with conversion specifiers unrelated to the parameters1601
Assign pointer to integerAnalyzerWarningAssigning memory address to variable expecting integer180046