c++ - How do I clear list of pair -

i want clear adj list main function each test case.

class graph { long long int v;    // no. of vertices list< pair<long long int,long long int> > *adj;  public: graph(long long int v);  // constructor  //clear previous values void clearlist(); }; void graph::clearlist() { //what should write here } 

well, since it's pointer list, should check existence first. , need decide if want keep object it's pointing after clear it, clear it:

void graph::clearlist() {     if ( adj ) {         adj->clear();     } } 

edit: couple of side notes depending on you're doing... if number of vertices member variable v what's in list, use adj->size() that. should consider not using pointer list , using list directly avoid manual lifetime management of adj in graph. finally, constructor implies you're declaring number of vertices front, maybe container more suitable, vector?