Memory leaks in c programs

Note that in using this macro trick, you lose the type checking which functions offer but it's a neat little trick I use a lot of times. I remember reading first chapter of Algorithms in a Nutshell which talked about this although it didn't include code. Just added in case you find it interesting. In addition to Als's answer which will wrap calls in your source code, if you're using gnu ld , you can have the linker wrap all calls presumably to malloc , realloc , calloc , and free at link time, irrespective of where they come from.

I tested with intentional memory leak - I have no idea why but google results are were incredibly terrible at finding this solution spread the word to help other devs! Here is how you can modify malloc, free hooks : Hooks for Malloc. Stack Overflow for Teams — Collaborate and share knowledge with a private group.

Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Detecting memory leaks in C programs? Ask Question. Asked 9 years, 11 months ago. Active 4 years, 8 months ago.

Viewed 63k times. Note: I would like to do this without any external utilities for practice. Jonathan Leffler k gold badges silver badges bronze badges. Mike G Mike G 4, 10 10 gold badges 43 43 silver badges 74 74 bronze badges. MitchWheat i mentioned that i cant use any external utilities — Mike G. Well, if this is for learning, you could learn about how valgrind does it Mike G: sure you can write your own.

Although excoriated by some, Writing Solid Code has some interesting ideas. For the excoriation, see the the review at ACCU. The book is old and dates from just after the C89 standard was finished and before all compilers supported it; it is a little quaint in places.

But memory allocation tracking is discussed extensively, and the general attitude 'Fortify your subsystems', etc is good. Add a comment. A memory leak may also happen when an object is stored in memory but cannot be accessed by the running code. In other words, leaks mean that dynamically-allocated memory cannot be released back to the operating system because the program no longer contains pointers that can access it.

If we examine the state of the program at line 25, just before executing the call to malloc for the second time, we observe:. These assignments are shown schematically below; both variables point to blocks of dynamically allocated memory. Once this happens, however, there is no remaining pointer that points to the shorter block. This is shown below:. Notice that the error message indicates the exact source line on which the problem occurs, not just where the block was allocated, which is a key issue in finding and fixing memory leaks.

I think it is worth repeating lifetime of local and global variables. I believe that should be after global variables are destroyed? I'm not sure on this point. But unless you're using some niche library that not many others are using, it is highly unlikely that your STL has memory leaks in such a common component. Show 2 more comments. Active Oldest Votes.

Chris 4, 4 4 gold badges 7 7 silver badges 27 27 bronze badges. Add a comment. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown.

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