Sipdroid's Blog

interesting things about virtual function

Posted in c++ by sipdroid on April 25, 2010

class Base{

virtual void test1()
printf("test1()in Base \n");

virtual void test2(int x=5)
 printf("test2(%d)in Base:\n",x);


class Derived: public Base


virtual void test1(int x=6) // the virtual keyword is not needed
printf("test1(%d)in Derived \n",x);

virtual void test2(int x=6)   //the virtual keyword is not needed
printf("test2(%d)in Derived\n",x);


Use use;
 Base* base = &use;
 base->test1();   //print out is : test1() in Base, the reason is test1() in Base and Derived has different signature, no override.

base->test2(); //print out is : test2(5) in Derived the test2() in override, but default value does not have virtual property.

Synchronized Age Map

Posted in c++ by sipdroid on April 19, 2010

I often need a synchronized map in multiple threads environment. developed a basic one , if  you have any comments to improve it, please let me know.

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 pthread_mutexattr_t mutex_attr;
 pthread_mutexattr_settype(&mutex_attr, PTHREAD_MUTEX_RECURSIVE);
 pthread_mutex_init(&mutex_, &mutex_attr);
 // pthread_mutex_init(&mutex_, NULL);

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