about C and C++_zerup

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about C and C++

(2012-04-17 15:35:44)

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it

char buf[10]={0};

buf[0]='a';

buf[1]='b';

cout<<buf<<endl;

int a = 10;

list<edge> *graph = new list<edge>[a];

edge e;

e.followee=10;

e.follower = 11;

graph[1].push_back(e);

char buf[100]={0};

char labelbuf[100]={0};

node lnode;

ifs.getline(buf,100);

//if(strlen(buf)!=0)

sscanf(buf,"%ld%s", &lnode.nodeid, labelbuf);

//scanf %s takes a char* not a string as para.

lnode.label = labelbuf;

cout<<"node: "<<lnode.nodeid<<"\tlabel: "<<lnode.label<<endl;

//itr != labellist.end();

for(itr=labellist.begin(); itr<labellist.end(); itr++){

if((*itr).nodeid == nodeid) return true;

else continue;

}

list<datatype> * followergraph = new list<datatype>[followers+1];

constructFollowerGraph(filename1,followers, followergraph);

//add a sentinel! PLUS ONE!

//how to use a iterator

list<int> intlist;

intlist.push_front(3);

intlist.push_front(4);

list<int>::iterator itr4intlist=intlist.begin();

itr4intlist++;

cout<<*(itr4intlist-1)<<endl;

return 0;

//iterator has five types: input, output, forward, bidirectional and random access;

//only the last type can be used as the form of "itr+n", where itr is a random access

// iterator and n is an integer

//map instance

typedef pair<long, string> NODE;

//constructor

map<long, string> label_map;

//insert a pair

long nodeid = 123;

string label="abc";

label_map[123]=label;

label_map.insert(NODE(nodeid, label));

//find a key using iterator

map<long, string>::iterator itr;

itr = label_map.find(nodeid);

cout<<(*itr).first<<endl;

//check the pointer of iterator

cout<<&itr<<endl;

map<long, string>::iterator *pitr = &itr;

//two ways to visit member variables

cout<<(*pitr)->first<<endl;

cout<<(**pitr).first<<endl;

error C2679: 二进制“=”: 没有找到接受“std::_Tree<_Traits>::const_iterator”类型的右操作数的运算符(或没有可接受的转换)

void printLabel(const map<datatype, string>& labelMap){ //as here comes a const

map<datatype, string>::iterator itr; //here a movable but unchangeable const_iterator must

for(itr = labelMap.begin(); itr != labelMap.end(); itr++){

cout<<(*itr).first<<'\t'<<(*itr).second<<endl;

}

const_iterator vs const ... iterator

vector<int> ivec;

vector<int>::const_iterator citer1 = ivec.begin(); //movable

const vector<int>::iterator citer2 = ivec.begin(); //changeable

*citer1 = 1; //error

*citer2 = 1; //right

++citer1; //right

++citer2; //error

typedef list<map<datatype, string>::iterator *> adjList;

//this definition is OK!

set<int> intset;

pair<set<int>::iterator, bool> *status = NULL;

status = &intset.insert(1);

cout<<&(status->first)<<"\t"<<status->second<<endl;

//print 001DFB00

status = &intset.insert(2);

cout<<&(status->first)<<"\t"<<status->second<<endl;

//print 001DFB24

status = &intset.insert(1);

cout<<&(status->first)<<"\t"<<status->second<<endl;

//print 001DFB48

//when insert a member into a set, create a new member and then insert it

//case is not that check whether the member and then create a new member

//more attention: size of a pair is bigger than expected

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