I got thread problem

karim24

the programm suppose to print 0->100 using 3 thread
i can't find the problem, in here it runs but it prints numbers with no meanning

#include <QCoreApplication>
#include<mythread.h>
#include<QThread>

int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
MyThread mt1,mt2,mt3;
mt1.start();
mt2.start();
mt3.start();
return a.exec();
}

#ifndef MYTHREAD_H
#define MYTHREAD_H
#include<QThread>
#include<QtCore>

mythread.h:
class MyThread:public QThread
{
public:
MyThread();
void run();
};

#endif // MYTHREAD_H

mythead.cpp:
#include "mythread.h"
#include<QThread>
#include<QDebug>
#include<QtCore>
MyThread::MyThread()
{
}
void MyThread:: run()
{
//qDebug()<<this->name<<"running hahah...";
for(int i=0;i<100;i++)
{
qDebug()<<i;
}
}

dbzhang800

Hi, what do you mean by

bq. it prints numbers with no meanning

karim24

i mean like that not actually no meanning but not what it's supposed to be
0
1
2

33
45
6
7
11

dbzhang800

Can you tell us which results are you expected?

The output looks good for me.
[quote author="karim24" date="1372386765"]i mean like that not actually no meanning but not what it's supposed to be
0
1
2

33
45
6
7
11[/quote]

karim24

I am expecting
0
1
2
3
4
5
6
.
.
.
99

MichelS

If you have multiple threads, it is the expected behavior to have those threads running simultaneously. So the output will almost never look like 0,1,2,3,...

dbzhang800

You want to make the three functions run one after another, instead of concurrent.So, thread isn't what you are looking for.
[quote author="karim24" date="1372421914"]I am expecting
0
1
2
3
4
5
6
.
.
.
99[/quote]

JKSH

[quote author="karim24" date="1372421914"]I am expecting
0
1
2
3
4
5
6
.
.
.
99[/quote]There is no good way to do that using threads. Just write
@
int main(int argc, char *argv[]) {
QCoreApplication a(argc, argv);

for (int i = 0; i < 100; ++i)
    qDebug() << i;

return a.exec&#40;&#41;;

}
@

[quote author="karim24" date="1372385882"]
void MyThread:: run() {
for(int i=0;i<100;i++) { qDebug()<<i; }
}
[/quote]If you create 3 of these threads, you will get 300 numbers. If you are "lucky", you will see:

0
0
0
1
1
1
2
2
2
...

But, as you have discovered in your example, the numbers will come out messed up because the threads will NOT wait for each other.

What do you plan to do with threads?

karim24

basically nothing in the meanwhile ,i am following a tutorial about qt in youtube , and he discussed threads in five or six videos ,and worked fine for him
http://www.youtube.com/watch?v=JaGqGhRW5Ks&list=SP2D1942A4688E9D63 .