I'm trying to iterate through a deque and erase the element with the smallest arrivalTime. The function works the first couple of times, then gives me the "iterator not dereferencable" error and stops working.
My Processor.h
:
#pragma once
#include <deque>
#include "Job.h"
#include <ctime>
using namespace std;
class Processor {
public:
deque<Job> priorityQueue;
Job runningJob;
bool isProcessing;
int processingTime;
int runningTime;
int overallJobs;
int numJobs[4]; //0 is A, 1 is B, 2 is C, 3 is D
int runningJobNumber;
int interruptedJobs;
Processor();
void simulate();
Job findNextJob();
};
My findNextJob()
:
Job Processor::findNextJob() {
Job nextJob = priorityQueue.front();
deque<Job>::const_iterator iter = priorityQueue.begin();
deque<Job>::const_iterator location;
while (iter <= priorityQueue.end()) {
if (iter->arrivalTime < nextJob.arrivalTime) {
nextJob = *iter;
location = iter;
iter++;
}
else {
iter++;
}
}
priorityQueue.erase(location);
return nextJob;
}
And finally, where I'm calling the function:
void Processor::simulate() {
srand(time(NULL));
char newJobType;
while (processingTime <= 50) {
newJobType = 65 + rand() % 4;
Job newJob(newJobType);
newJob.arrivalTime += runningTime;
processingTime += newJob.processingTime;
priorityQueue.push_back(newJob);
cout << endl << newJob.type << " " << newJob.arrivalTime;
runningTime++;
}
runningTime = 0;
int jobFinishTime;
Job nextJob;
nextJob = findNextJob();
while (priorityQueue.size()) {
cout << endl << runningTime << ") " << "Queue size: " << priorityQueue.size();
if (!isProcessing) {
cout << " CPU 1 Idle;";
if (nextJob.arrivalTime == runningTime) {
runningJob = nextJob;
//irrelevant code here
nextJob = findNextJob();
}
}
if (isProcessing && (runningJob.arrivalTime + runningJob.processingTime) != runningTime) {
//irrelevant code here
if (nextJob.arrivalTime <= runningTime) {
runningJob = nextJob;
//irrelevant code here
nextJob = findNextJob();
}
}
if (nextJob.priority > runningJob.priority && nextJob.arrivalTime <= runningTime) {
//irrelevant code here
}
runningTime++;
}
}
findNextJob()
runs successfully two or three times then gives me the error. Any help would be appreciated.
In C++, the end iterator "points to" one past the last element.
findNextJob allows the iterator iter
to become equal to priorityQueue.end()
, so dereferencing it is invalid.
while (iter <= priorityQueue.end()) {
// ...
}
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