Reddit
reddit.com › r/c_programming › how do you prevent dangling pointers in your code?
r/C_Programming on Reddit: How do you prevent dangling pointers in your code?
March 4, 2024 -
I think memory safety is an architectural property, and not of the language.
I'm trying to decide what architectural decisions to take so future team members don't mistakenly create dangling pointers.
Specifically I want to prevent the cases when someone stores a pointer in some struct, and forgets about it, so if the underlying memory is freed or worse, reallocated, we'll have a serious problem.
I have found 3 options to prevent this ...
-
Thug it out: Be careful while coding, and teach your team to be careful. This is hard.
-
Never store a pointer: Create local pointers inside functions for easy use, but never store them inside some struct. Use integer indices if necessary. This seems easy to do, and most safe. Example: Use local variable
int *x = object->internal_object->data[99];inside a function, but never store it in any struct. -
Use a stack based allocator to delete and recreate the whole state every frame: This is difficult, but game engines use this technique heavily. I don't wish to use it, but its most elegant.
Thanks
Top answer 1 of 29
55
good practices and valgrind
2 of 29
29
Option 1. Use AddressSanitizer to catch memory safety errors, plus SonarLint to find code smells.
Scaler
scaler.com › home › topics › dangling pointer in c
Dangling Pointer in C - Scaler Topics
June 14, 2022 - We can avoid these conditions by assigning NULL in case of deallocation of memory and using static variables in case of variables having local scope. We should assign NULL to the ptr pointer as soon as the memory block pointed by the ptr has been deallocated using the free() function to avoid ...
How do you prevent dangling pointers in your code?
good practices and valgrind More on reddit.com
55
24
March 4, 2024How to handle dangling pointers in a game engine?
You want reference counting. You can't free the memory until all references (pointers) have gone out-of-scope. "Freeing when you want" is a misfeature, as you've found. BTW, C++ smart pointers are reference counting (atomic incs / decs, but no lock protecting the underlying object). More on reddit.com
27
41
June 17, 2021Dangling pointers in C (forgetting to set pointers to null after free) - is this macro a good solution? #define SAFE_FREE(ptr) do { free(ptr); ptr = NULL; } while(0)
I noticed today that if you free(ptr), and forget to set it to NULL, then you have no way to know later, when trying to access or modify it, that it was actually freed! It will keep pointing to the same address in memory, but that address may now be of other, unrelated variables. This may not even cause the program to crash, right? Correct, dereferencing a pointer after the end of the lifetime of the object it points to is undefined behavior and technically, the program is allowed to do absolutely anything from that point on. This doesn't just apply to memory allocated with malloc. It also applies to local variables, whose lifetime ends when at the end of the corresponding function or block. Is there any downside to always using this macro, rather than always writing 2 lines manually? Well, the C preprocessor is just a dumb text substitution engine. So in terms of the compiled code, using your macro is exactly the same as writing the statements directly. (The do { ... } while (0) construct is a trick to make the macro behave correctly as though it were a single statement.) The biggest issue I have with your macro is that the name is misleading. It's not really "safe" because it doesn't prevent the underlying problem. In particular, if you ever pass around copies of a pointer (which is common) then just setting one copy to NULL doesn't affect the other copies. So if you're uncertain whether an object has been freed, then checking whether the pointer is NULL is not reliable on its own, unless you also know that nowhere else in your program is calling free on a copy of the pointer. And likewise, calling SAFE_FREE on a local pointer variable is not necessary when the pointer variable is going out of scope. If the variable is disappearing, it doesn't matter whether you set it to NULL. (In fact, the compiler would probably optimize out the assignment statement.) If I were reading your code and I saw something like SAFE_FREE, I would have to look up the macro definition anyway to see what it was actually doing in terms of memory management. Writing free(ptr); ptr = NULL; directly is clearer, in my opinion. In general, C is a language that demands you constantly pay attention to memory management at all times. This is just a habit you need to develop. Other languages provide better tools to assist you with this. For instance, C++ has "smart pointers" that act as an abstraction layer above regular pointers. The smart pointer is responsible for knowing when it's safe to call free on the underlying pointer. More on reddit.com
12
7
July 16, 2025How does a dangling pointer in C occur?
It occurs when a pointer continues to reference memory after it has been freed, gone out of scope, or returned from a function.
wscubetech.com
wscubetech.com › resources › c-programming › dangling-pointer
Dangling Pointer in C Language (Explained With Examples)
What are the risks of using a dangling pointer in C?
Using a dangling pointer in C can lead to segmentation faults, memory corruption, data loss, and undefined program behavior. The worst part is that some bugs caused by dangling pointers might not crash immediately, making them hard to detect and debug. These bugs can silently alter program logic and corrupt data.
upgrad.com
upgrad.com › home › tutorials › software & tech › dangling pointer in c
Stop Bugs: Dangling Pointer in C Explained
What causes dangling pointers in C?
Dangling pointers are typically caused by freeing dynamically allocated memory and then continuing to use the pointer, returning the address of local variables, or using pointers to variables that have gone out of scope. These situations leave the pointer pointing to memory that is no longer valid for access.
upgrad.com
upgrad.com › home › tutorials › software & tech › dangling pointer in c
Stop Bugs: Dangling Pointer in C Explained
00:50
What is Dangling Pointer in C Language? #cprogramming #ccode - YouTube
08:09
Understanding Dangling Pointers in C - YouTube
09:02
What is Dangling Pointer in C ? Explained with Examples | C ...
04:10
dangling pointer in c with example | What is Dangling Pointer? ...
05:11
Understanding the Dangling Pointers - YouTube
10:59
C language - Class 34 : Dangling pointer in c programming language ...
Board Infinity
boardinfinity.com › blog › dangling-pointer-in-c
Dangling Pointer in C: Causes, Types, Fixes & Examples
June 16, 2026 - State ownership in function names or documentation, avoid returning pointers to temporary data, prefer caller-owned buffers for outputs, and provide clear create/destroy pairs for heap-owned objects.
TutorialsPoint
tutorialspoint.com › cprogramming › c_dangling_pointers.htm
Dangling Pointers in C
C doesnt have the feature of automatic garbage collection, so we need to carefully manage the dynamically allocated memory. To fix the issue of dangling pointers or to avoid them altogether, you need to apply proper memory management and try to avoid situations where you may end up getting dangling pointers.
Upgrad
upgrad.com › home › tutorials › software & tech › dangling pointer in c
Stop Bugs: Dangling Pointer in C Explained
October 4, 2024 - The use of `static` ensures `safeVar` persists even after `assignPointer()` exits, avoiding the dangling pointer in C issue. ... If you need to return a reference that lasts longer than a function's scope—but don’t want to dynamically allocate memory—`static` or global variables are an option.
Unstop
unstop.com › home › blog › dangling pointer in c language explained (with code examples)
Dangling Pointer In C Language Explained (With Code Examples)
March 12, 2024 - To prevent the creation of dangling pointers in C due to the deallocation of memory using free(), it is essential to adopt disciplined memory management practices. That is, immediately after freeing memory with free(), you must set the pointer ...
WsCube Tech
wscubetech.com › resources › c-programming › dangling-pointer
Dangling Pointer in C Language (Explained With Examples)
July 27, 2026 - Learn in this tutorial about Dangling Pointer in C with examples. Understand how it is created, the issues it causes, and methods to avoid it in C programs.
NxtWave
ccbp.in › blog › articles › dangling-pointer-in-c
Dangling Pointers in C: Causes, Risks & Prevention
It reduces the risk of memory leaks and dangling pointers. 2. Avoid Returning Local Addresses: Never return the address of a local variable. Instead, use dynamic memory allocation (malloc()/new) or static variables so the pointer remains valid.
Electro4u
electro4u.net › blog › what-is-a-dangling-pointer-how-to-avoid-the-dangling-pointer-358
Dangling Pointer in C: Definition, Causes, and Prevention Techniques
Never return a pointer to a local variable or a dynamically allocated memory that has already been freed, as the memory will no longer be valid. Use dynamic memory allocation functions like malloc, calloc, and realloc to manage memory dynamically and avoid memory leaks and dangling pointers.
LearnMandu
learnmandu.com › home › blog › memc blog › dangling pointers in c - a comprehensive guide to prevention
Dangling Pointers in C - A Comprehensive Guide to Prevention
March 29, 2026 - Nullify Pointers Immediately: The golden rule of C pointer management is free(ptr); ptr = NULL;. A NULL pointer won't secretly corrupt data; it provides a clean, immediate crash (Segfault) which is vastly easier to debug.
Nerdsdostuff
nerdsdostuff.com › c_programming › dangling-pointer-in-c
Dangling Pointer in C - Nerds Do Stuff
May 31, 2026 - A dangling pointer refers to invalid ... represent no valid object. Avoid using pointers after free(), do not return local addresses, watch variable scope, and set pointers to NULL when appropriate....
Open Source For You
opensourceforu.com › home › audience › developers › dangling pointers avoid them strictly!
Dangling Pointers Avoid them Strictly!
June 9, 2016 - In the C programming language, deleting an object from memory explicitly or by destroying the stack frame on the return of the control does not alter associated pointers as seen in Case 1 and Case 3. The pointer still points to the same location ...
Tutorialforgeeks
tutorialforgeeks.com › dangling-pointer-in-c
Dangling Pointer in C | TutorialforGeeks
Since dangling pointers can cause crashes, data corruption, and security issues, it is important to handle memory carefully. Setting pointers to NULL after freeing memory and understanding variable lifetimes are effective ways to avoid dangling ...
CodingEasily
codingeasily.in › home › blog › dangling pointer in c: 3 causes and how to avoid it
Dangling Pointer in C: 3 Causes and How to Avoid It | CodingEasily
July 3, 2026 - Set the pointer to NULL immediately after free(), never return addresses of local variables, and match pointer lifetime with the memory it points to. → Dynamic Memory in C Tutorial → C Pointers – Complete Guide → Blog: Wild Pointer in ...
GeeksforGeeks
geeksforgeeks.org › c language › dangling-void-null-wild-pointers
Dangling, Void , Null and Wild Pointers in C - GeeksforGeeks
July 11, 2026 - Accessing such a pointer can lead to undefined behavior and program errors. It usually occurs after freeing dynamically allocated memory or when a local variable goes out of scope. Using a dangling pointer may cause unexpected behavior, crashes, or bugs in the program.
Javatpoint
javatpoint.com › dangling-pointers-in-c
Dangling Pointers in C - javatpoint
September 4, 2014 - Dangling Pointers in C with Tutorial or what is c programming, C language with programming examples for beginners and professionals covering concepts, control statements, c array, c pointers, c structures, c union, c strings and more.
TechTarget
techtarget.com › searchsecurity › tip › How-to-avoid-dangling-pointers-Tiny-programming-errors-leave-serious-security-vulnerabilities
What dangling pointers are and how to avoid them | TechTarget
July 18, 2024 - Dangling pointers occur when a programmer creates, uses and then frees an object in memory but does not change the object's pointer value accordingly -- in this case, to a null pointer. Instead, the pointer inaccurately refers to the memory location of the deallocated memory.
Runebook.dev
runebook.dev › en › docs › c › language › pointer
C Pointers: Avoiding Wild and Dangling Pointers
Alternative Solution Always initialize your pointers! The safest way is to set them to NULL (a special value that indicates the pointer doesn't point to any valid memory address).
Wikipedia
en.wikipedia.org › wiki › Dangling_pointer
Dangling pointer - Wikipedia
August 8, 2026 - Another frequent source of dangling pointers is a jumbled combination of malloc() and free() library calls: a pointer becomes dangling when the block of memory it points to is freed. As with the previous example one way to avoid this is to make sure to reset the pointer to null after freeing ...
Developer Insider
developerinsider.co › what-is-dangling-pointer-with-cause-and-how-to-avoid-it
What is Dangling Pointer with Cause and How to avoid it?
March 29, 2018 - We can avoid the dangling pointer errors by initialize pointer to NULL, after de-allocating memory, so that pointer will be no longer dangling.