deque::operator 和 deque::at

說明如何使用 deque::operator [ 和 deque::at Visual C++ 標準樣板程式庫 (STL) 函式。

const_reference operator[](
   size_type Pos
) const;
reference operator[](
   size_type Pos
);
const_reference operator[](
   difference_type _N
) const;
reference operator[](
   difference_type _N
) const;
const_reference at(
   size_type Pos
) const;
reference at(
   size_type Pos
); bool empty( ) const;

備註

注意事項
在原型中的類別/參數名稱不相符的標頭檔中的版本。某些已修改以提高可讀性。

運算子 [成員函式會傳回位置受控制序列的項目之參考 Pos。如果該位置不正確的是未定義的行為。在 成員函式會傳回位置受控制序列的項目之參考 Pos。如果該位置不正確，函式會擲回的物件類別的out_of_range。空 成員函式會傳回 ，則為 true 為空的受控制序列。

範例

// operator.cpp
// compile with: /EHsc
//
// Functions:
//    operator[]
//    at
//    empty
//    push_back
//    begin
//    end

#include <iostream>
#include <deque>

using namespace std;


typedef deque<char >  CHARDEQUE;
void print_contents (CHARDEQUE  deque, char*);

int main()
{
    //create an empty deque a
    CHARDEQUE  a;

    //check whether it is empty
    if(a.empty())
        cout<<"a is empty"<<endl;
    else
        cout<<"a is not empty"<<endl;

    //inset A, B, C and D  to a
    a.push_back('A');
    a.push_back('B');
    a.push_back('C');
    a.push_back('D');

    //check again whether a is empty
    if(a.empty())
        cout<<"a is empty"<<endl;
    else
        cout<<"a is not empty"<<endl;

    //print out the contents

    print_contents (a,"a");

    cout <<"The first element of a is " <<a[0] <<endl;
    cout <<"The first element of a is " <<a.at(0) <<endl;

    cout <<"The last element of a is " <<a[a.size()-1] <<endl;
    cout <<"The last element of a is " <<a.at(a.size()-1) <<endl;
}

//function to print the contents of deque
void print_contents (CHARDEQUE  deque, char *name)
{
    CHARDEQUE::iterator pdeque;

    cout <<"The contents of "<< name <<" :";

    for(pdeque = deque.begin();
        pdeque != deque.end();
        pdeque++)
        {
            cout <<" "  << *pdeque;
        }
    cout<<endl;
}

需求

標頭: < deque >

請參閱

概念

標準樣板程式庫範例