Problem with sorting a vector of struct in C++

Question

so I am basically trying to make a function that sorts a vector of a struct called tasks based on the task's priority. My program crashes whenever the given vector has two items or more dunno what's wrong with my code help! n thanks!

void sort_tasks(std::vector<tasks> &tasks_list)
{
    if(!tasks_list.empty()){
        bool result = false;
        do
        {
            int counter = 0;
            for(std::vector<tasks>::iterator i = tasks_list.begin(); i != tasks_list.end(); i++)
            {
                if(counter < tasks_list.size())
                {
                    auto j = i++;
                    if(i->task_priority < j->task_priority) {
                        auto temp = *j;
                        *j = *i;
                        *i = temp;

                        if(!result) {
                            result = true;
                        }
                    }
                }
                counter++;
            }
        } while(result);

    }
}

Can you use std::sort? It will be much easier and more efficient than bubble sort. — Yksisarvinen
– Yksisarvinen, Commented Jun 9, 2020 at 10:59
And when you used your debugger to run your program, what did you see? This is precisely what a debugger is for. If you don't know how to use a debugger this is a good opportunity to learn how to use it to run your program one line at a time, monitor all variables and their values as they change, and analyse your program's logical execution flow. Knowing how to use a debugger is a required skill for every C++ developer, no exceptions. With your debugger's help you should be able to quickly find all bugs in this and all future programs you write, without having to ask anyone for help. — Sam Varshavchik
– Sam Varshavchik, Commented Jun 9, 2020 at 11:00
Learning how to debug your programs is a crucial skill to know what is going on during your program's run. — crashmstr
– crashmstr, Commented Jun 9, 2020 at 11:00
Think about when i is "pointing" to the last element in the vector. When you then do i++ where will it "point"? — Some programmer dude
– Some programmer dude, Commented Jun 9, 2020 at 11:00

MatthieuL · Accepted Answer · 2020-06-09 11:00:18Z

1

Here auto j = i++; you don't check if i is tasks_list.end() after the increment.

You check it well in the for but you have to check it here too because you increment the iterator.

answered Jun 9, 2020 at 11:00

MatthieuL

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1 Comment

Wolvington Over a year ago

that part of the code was supposed to be executed only if 'i' was inferior to the vector's size but ye since the index starts from 0 it has to be (i < vector.size() - 1). Thank you.

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