Error: Free(): Invalid Next Size (Fast):

Error: free(): invalid next size (fast):

It means that you have a memory error. You may be trying to free a pointer that wasn't allocated by malloc (or delete an object that wasn't created by new) or you may be trying to free/delete such an object more than once. You may be overflowing a buffer or otherwise writing to memory to which you shouldn't be writing, causing heap corruption.

Any number of programming errors can cause this problem. You need to use a debugger, get a backtrace, and see what your program is doing when the error occurs. If that fails and you determine you have corrupted the heap at some previous point in time, you may be in for some painful debugging (it may not be too painful if the project is small enough that you can tackle it piece by piece).

Error free(): Invalid next size (fast)

Use malloc(row_size * num_rows * sizeof(int)) .

You didn't malloc enough memory so your loop wrote past your malloc()ed memory. I'm surprised you didn't just get a segmentation fault.

Free() : invalid next size (fast) error

Change this:

char* copy = malloc(sizeof(line));

to this:

char* copy = malloc(strlen(line) + 1);

The first allocates space for the size of line, which is a POINTER!

While the second, allocates space equal to the length of the string that line points to, plus one, for the NULL terminator (please don't forget that and you will live a happier c-life)! ;)

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BTW, I believe that it's more common to write the comments of your code above the line of code (rather than next to it). :)

C++ Runtime Error: free(): invalid next size (fast)

Does the issue come from the fact that src and dst go out of scope at the end of iteration of the for loop?

No, these valuea are pushed into the vector, before going out of scope, so this is fine.

C++ Runtime Error: free(): invalid next size (fast)

This means that heap is corrupted. Valgrind can be helpful in this cases.

That memory error is not coming from std::vector, but from your pointers. Somewhere, you free something you shouldn't? That may be caused by bad memory allocation on your behalf (something has not been allocated as you desire it to). Who knows with the code you posted.

In any, case, you should really use Valgrind to track that error down.

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PS: Do you really need to use that many pointers? I mean in your functions, you could just have passed your vector by reference, like this:

void addMutations(vector<Gene*>& genome) {

and then do:

genome.at(i)->sourceNeuronID;

and so on.

Pointers are great (e.g. in polymorphism), but you should use them with caution and of course, use them when needed (Pan Metron Ariston).

C++ free(): invalid next size (fast)

The line

vector<vector<int>> result(grid.size(), vector<int>(grid.size(), 0));

creates square grid, not a rectangular grid. You probably meant to use:

vector<vector<int>> result(grid.size(), vector<int>(grid[0].size(), 0));
                                                        ^^^^

I suggest using:

int rows = grid.size();
int cols = grid[0].size();
vector<vector<int>> result(rows, vector<int>(cols, 0));

C: free(): invalid next size (fast)

Change

  struct lnode *myNode = malloc(sizeof(struct  lnode*));

to

  struct lnode *myNode = malloc(sizeof(struct  lnode));

and

  myNode->word = (char*)malloc((strlen(word))*sizeof(char));

to

  myNode->word = (char*)malloc((strlen(word)+1)*sizeof(char));

Thank you for going through the effort to make the smallest test case you could.

free(): invalid next size (fast): when use posix_memalign

Within this call:

rb.create(4);

the parameter count of create member function has value 4. According to

size_t page_cnt = (count * sizeof(void*)) / page_sz + 1;

page_cnt has value 1. In

ret = posix_memalign(&ptr_mem_, page_sz, page_cnt);

you ask posix_memalign to allocate page_cnt bytes, therefore, just 1 byte, according to the documentation:

int posix_memalign(void **memptr, size_t alignment, size_t size);

The function posix_memalign() allocates size bytes...

Don't you want to allocate page_cnt pages instead? If so, change the call to:

ret = posix_memalign(&ptr_mem_, page_sz, page_cnt * page_sz);

free(): invalid next size (fast) after several calls

The problem is in one of your loops. As said in this post on Error: free(): invalid next size (fast):

You may be overflowing a buffer or otherwise writing to memory to which you shouldn't be writing, causing heap corruption.

My best guess is this loop:

for (i=1, q=1; q; ++i) {
  q0 = p[i];
  p[i] += q;
  q = q0;
}

if p array is not 0 terminated, this will overwrite memory in the heap.

That being said, if you use std::vector instead of a manually allocated array, your code would be much clearer.

C++: free(): invalid next size (fast)

char* hostname_Client(){
    char hostbuffer[1024]={0};
        gethostname(hostbuffer,sizeof(hostbuffer));
    char *hostname;
    strcpy(hostname,hostbuffer);
        return hostname;
}

You never initialize hostname, so it has some random value and doesn't point to anything. Then you pass its random value to strcpy and tell it to copy the string to some random location.

Since you're using C++, you may wish to consider using std::string instead of char * because it does most of the memory management for you.

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