iostream flag

Binary -------------------------

ifs.read(as_bytes(i),sizeof(int));

ofs.write(as_bytes(v[i]),sizeof(int));

template<class T>

char* as_bytes(T& i){

void* addr=&i;

return static_cast<char*>(addr);

}

---------------------------------

fstream fs(name.c_str());

if (!fs) error("can't open",name);

fs.seekg(5); //Move reading position

char ch;

fs>>ch;

cout<<"character[5] is"<<ch<<'('<<int(ch)<<")/n";

fs.seekp(1); //Move writing position

fs<<'y';

---------------------------------

ofstream ofs(name,ios_base::app); //末尾追加

fstream fs("myfile",ios_base::in|ios_base::out); //Both In & Out

if (!fs) ifstream ifs("no-file-of-this-name"); //打开一个不存在文件，会自建。

ios_base::binary <-> 2进制方式存取内存

cout<<general<<setprecision(8)<<1234.5678<<endl;

cout<<123456<<'|'<<setw(4)<<123456<<'|'<<setw(8)<<123456<<'|'<<endl;

cout<<showbase<<1234<<oct<<1234<<hex<<1234<<endl; //OPT

cin.unsetf(ios::dec);

cin.unsetf(ios::oct);

cin.unsetf(ios::hex);

cin>>a>>b>>c>>d;

1234 0x4d2 02322 02322

->

1234 1234 1234 1234

cout<<1234.5678<<fixed<<1234.5678<<scientific<<1234.5678;

void fill_vector(istream& ist,vector<int>& v,char terminator){

int i=0;

while(ist>>i) v.push_back(i);

if(ist.eof()) return;

if(ist.bad()) error("ist is bad");

if(ist.fail()) {

ist.clear(); //清除Fail状态,--为了是否terminator了？

char c;

ist>>c;

if (c!=terminator){

ist.unget(); //put charactor back

ist.clear(ios_base::failbit); //set state to fail()

}

}

}

int get_int(int low,int high,const string& greeting,const string& sorry){

cout<<greeting<<":["<<low<<':'<<high<<"/n";

while(true){

int n=get_int();

if(low<=n&&n<=high) return n;

cout<<soory<<":["<<low<<':'<<high<<"/n";

}

}

int get_int(int low,int high){

int n=0;

while(true){

if(cin>>n) return n;

cout<<"Sorry,that was nott a number"<<endl;

skip_to_int();

}

}

void skip_to_int(){

if(cin.fail()){

cin.clear();

char ch;

while(cin>>ch){

if(isdigit(ch)){

cin.unget();

return;

}

}

}

error("no input!");

}

ostream& operator<<(ostream& os,const Data& d){

return os<<'('<<d.year()<<','<<d.month()<<','<<d.day()<<')';

}

istream& operator>>(istream& is,Date& dd){

int y,m,d;

char ch1,ch2,ch3,ch4;

is>>ch1>>y>>ch2>>m>>ch3>>d>>ch4;

if (!is) return is;

if (ch1!='('||ch2!=','||ch3!=','||ch4!=')'){

is.clear(ios_base::failbit);

return is;

}

dd=Date(y,Date::Month(m),d);

return is;

}