Error: pointer being freed was not allocated

[Rodev]

Hello,

I am working on a "line-oriented text editor" for my CS course and I must use the List container.

I created a member function that prints all elements from my List in a specific range. I am sure there must be a better way to code this, but my current code is below:

Quick example:
List {1, 2, 3, 4, 5, 6};
print(List, 1, 2);
The output should be 1 and 2.

std::list<std::string> print(std::list<std::string> list, int first_line, int last_line)
{    
    std::list<std::string>::iterator it = list.begin();
    
    std::advance(it, first_line);
    
    for (auto i = 10; i > last_line + 1; --i)
    {
        list.pop_back();
    }
    
    for (; it != list.end(); ++it)
    {
        std::cout << *it << std::endl;
    }
    
    return list;
}

This function runs perfectly when I compile it using an online c++ compiler and I get the output I want. Of course, I tested it alone.

However, when I include the above function in my project (inside a Class) and compile it, when I call the function I get the following error message:

a.out(2586,0x7fffbbb313c0) malloc: *** error for object 0x7fff501c76e8: pointer being freed was not allocated
*** set a breakpoint in malloc_error_break to debug
Abort trap: 6

I am using Xcode 8 to write my code, but I am compiling it from my Terminal using clang++ for C++11.

Unfortunately, I have no idea why I am getting this error. Any suggestion/help?

Thanks!

obs: first post here, if I did something wrong, just let me know! :)

[jonnin]

at a quick glance, pop-back is probably being called on something that does not exist.

[Rodev]

jonnin,

Thanks a lot!!! :D

You are totally right! my for loops for the pop_back() had "i = 10" but I only have 5 elements. I changed the value of "i" to 5 and it worked!

For my own learning, why did you think it was the pop_back? By reading the error, I had no clue.

Again, thanks!