Hello, I made this short program to understand a bit of multithreading butits no

Question

Hello,

I made this short program to understand a bit of multithreading butits not working. Could anyone please take a look at it?

#include <iostream>
#include <pthread.h>

using namespace std;

void *server( void *ptr );// thread function
void *listener (void *ptr);

struct variable {
    int n;
    char y;
};


int main(int argc, char **argv)


{

    variable *var1, *var2;
    cout<<"Enter both n"<<endl;
    cin>>var1->n>>var2->n;
    cout<<"Enter both y"<<endl;
    cin>>var1->y>>var2->y;

    int th1, th2;
    pthread_t thread1, thread2;


    th1 = pthread_create( &thread1, NULL,server, (void*) var1);
    th2 = pthread_create( &thread2, NULL,listener, (void*) var2);
   
    pthread_join( thread1, NULL);
     pthread_join( thread2, NULL);

     cout<<"Thread 1 returns:"<<th1<<endl;
    cout<<"Thread 1 returns:"<<th1<<endl;

    
    return 0;

}

void *server( void *ptr )
{
    variable *var3;
    var3 = (variable*)ptr;
   cout<<var3->n<<var3->y<<endl;
   
}

void *listener (void *ptr)
{
    variable *var4;
    var4 = (variable*)ptr;
   cout<<var4->n<<var4->y<<endl;

}
The errors I am getting are:

Compiling...
DCN.CPP
C:Program FilesMicrosoft VisualStudioMyProjectsProjectDCN.CPP(22) : warning C4700: localvariable 'var2' used without having been initialized
C:Program FilesMicrosoft VisualStudioMyProjectsProjectDCN.CPP(22) : warning C4700: localvariable 'var1' used without having been initialized
C:Program FilesMicrosoft VisualStudioMyProjectsProjectDCN.CPP(50) : error C4716: 'server' :must return a value
C:Program FilesMicrosoft VisualStudioMyProjectsProjectDCN.CPP(58) : error C4716: 'listener' :must return a value
Error executing cl.exe.

DCN.OBJ - 2 error(s), 2 warning(s)

------------------------------------------
Thank you.

Explanation / Answer

//Hello, You must use g++ compilerto compile it in linux environment. // example : g++ test.cpp-lpthread
//Hope this will helpyou.
#include <iostream> #include <pthread.h>
using namespace std;
void *server( void *ptr );// thread function void *listener (void *ptr);
struct variable {    int n;    char y; };

int main(int argc, char **argv)

{
   variable var1, var2; /* you need already allocated variablesnot pointer */       cout<<"Enter bothn"<<endl;    cin>>var1.n>>var2.n;    cout<<"Enter bothy"<<endl;    cin>>var1.y>>var2.y;
   int th1, th2;    pthread_t thread1, thread2;

   th1 = pthread_create( &thread1, NULL,server, (void*) (&var1));    th2 = pthread_create( &thread2, NULL,listener, (void*) (&var2));       pthread_join( thread1, NULL);    pthread_join( thread2, NULL);    cout<<"Thread 1 returns:"<<th1<<endl;    cout<<"Thread 1 returns:"<<th1<<endl;
         return 0;
}
void *server( void *ptr ) {    variable *var3;    var3 = (variable*)ptr;    cout<<var3->n<<var3->y<<endl;    }
void *listener (void *ptr) {    variable *var4;    var4 = (variable*)ptr;    cout<<var4->n<<var4->y<<endl;
}
#include <iostream> #include <pthread.h>
using namespace std;
void *server( void *ptr );// thread function void *listener (void *ptr);
struct variable {    int n;    char y; };

int main(int argc, char **argv)

{
   variable var1, var2; /* you need already allocated variablesnot pointer */       cout<<"Enter bothn"<<endl;    cin>>var1.n>>var2.n;    cout<<"Enter bothy"<<endl;    cin>>var1.y>>var2.y;
   int th1, th2;    pthread_t thread1, thread2;

   th1 = pthread_create( &thread1, NULL,server, (void*) (&var1));    th2 = pthread_create( &thread2, NULL,listener, (void*) (&var2));       pthread_join( thread1, NULL);    pthread_join( thread2, NULL);    cout<<"Thread 1 returns:"<<th1<<endl;    cout<<"Thread 1 returns:"<<th1<<endl;
         return 0;
}
void *server( void *ptr ) {    variable *var3;    var3 = (variable*)ptr;    cout<<var3->n<<var3->y<<endl;    }
void *listener (void *ptr) {    variable *var4;    var4 = (variable*)ptr;    cout<<var4->n<<var4->y<<endl;
}

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