asked on

InterlockedExchange for string

When write to variables that are used in multiple threads, I read that I need to use InterlockedExchange() to lock the variable. This function works great for integers but I have a variable that is a string. Is there a function to do the same thing for strings.

ASKER CERTIFIED SOLUTION

jkr

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jkr

Oh, and when you no longer need the CRITICAL_SECTION, clean up using

DeleteCriticalSection(&g_cs);

chip3d

a nicer way would be to encapsulate the whole CRITICAL_SECTION stuff in a RAII object like:

class Lock
{
public:
Lock() {InitializeCriticalSection(&lock_);}
~Lock() {DeleteCriticalSection(&lock_);}

void lock () const
{
EnterCriticalSection (&lock_);
}

bool unlock () const
{
LeaveCriticalSection (&lock_);
return true;
}

private:
mutable CRITICAL_SECTION lock_;

// no copy and assignment
Lock (const Lock &src);
Lock& operator= (const Lock &src);
};

chip3d

sorry

bool unlock () const
{
LeaveCriticalSection (&lock_);
return true;
}

should be

void unlock () const
{
LeaveCriticalSection (&lock_);
}

regards

chip3d

than all you need is a other class like

class Locker
{
public:
explicit Locker (Lock &lock) : lock_(lock) {lock_.lock();}
~Locker() {lock_.unlock();}

private:
Lock& lock_;

// no copy and assignment
Locker (const Locker &src);
Locker& operator= (const Locker &src);
};

so you could use is it like

....

Lock lock;
lock.lock();

your string code...

lock.unlock;

or as RAII

Lock lock; // as member of an object or in function....

Locker lockthis(lock);
your string code...

// the lock will be release as soon as lockthis will be out of scope

regards

jkr

Even though a wrapper class is nice, I'd rather start out with the basics when learning a new API. Just my 2 Cents here, though.