怎样构建一个结构的vector或list?
假设有如下一个结构
struct Info
{
char name[20];
unsigned int age;
}
声明语句如下:
vector <Info> CustomerInfo
请问怎样给该结构赋值并将其放入CustomerInfo中，以及从中取值，教材上的例子全是简单类型。
问题点数：20、回复次数：9Top
1 楼bigmouse2002（平风造雨*四无君）回复于 2005-04-02 03:49:42 得分 0
#ifndef MINI_VECTOR
#define MINI_VECTOR
#include "d_except.h" // include exception classes
using namespace std;
template <typename T>
class miniVector
{
public:
miniVector(int size = 0);
// constructor.
// Postconditions: allocates array with size number of elements
// and capacity. elements are initialized to T(), the default
// value for type T
miniVector(const miniVector<T>& obj);
// copy constructor
// Postcondition: creates current vector as a copy of obj
~miniVector();
// destructor
// Postcondition: the dynamic array is destroyed
miniVector& operator= (const miniVector<T>& rhs);
// assignment operator.
// Postcondition: current vector holds the same data
// as rhs
T& back();
// return the element at the rear of the vector.
// Precondition: the vector is not empty. if vector
// is empty, throws the underflowError exception
const T& back() const;
// const version used when miniVector object is a constant
T& operator[] (int i);
// provides general access to elements using an index.
// Precondition: 0 <= i < vSize. if the index is out
// of range, throws the indexRangeError exception
const T& operator[] (int i) const;
// const version used when miniVector object is a constant
void push_back(const T& item);
// insert item at the rear of the vector.
// Postcondition: the vector size is increased by 1
void pop_back();
// remove element at the rear of the vector.
// Precondition: vector is not empty. if the vector is
// empty, throws the underflowError exception
int size() const;
// return current list size
bool empty() const;
// return true if vector is empty and false otherwise
int capacity() const;
// return the current capacity of the vector
private:
int vCapacity; // amount of available space
int vSize; // number of elements in the list
T *vArr; // the dynamic array
void reserve(int n, bool copy);
// called by public functions only if n > vCapacity. expands
// the vector capacity to n elements, copies the existing
// elements to the new space if copy == true, and deletes
// the old dynamic array. throws the memoryAllocationError
// exception if memory allocation fails
};
// set the capacity to n elements
template <typename T>
void miniVector<T>::reserve(int n, bool copy)
{
T *newArr;
int i;
// allocate a new dynamic array with n elements
newArr = new T[n];
if (newArr == NULL)
throw memoryAllocationError(
"miniVector reserve(): memory allocation failure");
// if copy is true, copy elements from the old list to the new list
if (copy)
for(i = 0; i < vSize; i++)
newArr[i] = vArr[i];
// delete original dynamic array. if vArr is NULL, the vector was
// originally empty and there is no memory to delete
if (vArr != NULL)
delete [] vArr;
// set vArr to the value newArr. update vCapacity
vArr = newArr;
vCapacity = n;
}
// constructor. initialize vSize and vCapacity.
// allocate a dynamic array of vSize integers
// and initialize the array with T()
template <typename T>
miniVector<T>::miniVector(int size):
vSize(0), vCapacity(0), vArr(NULL)
{
int i;
// if size is 0, vSize/vCapacity are 0 and vArr is NULL.
// just return
if (size == 0)
return;
// set capacity to size. since we are building the vector,
// copy is false
reserve(size, false);
// assign size to vSize
vSize = size;
// copy T() into each vector element
for (i=0;i < vSize;i++)
vArr[i] = T();
}
// copy constructor. make the current object a copy of obj.
// for starters, use initialization list to create an empty
// vector
template <typename T>
miniVector<T>::miniVector (const miniVector<T>& obj):
vSize(0), vCapacity(0), vArr(NULL)
{
int i;
// if size is 0, vSize/vCapacity are 0 and vArr is NULL.
// just return
if (obj.vSize == 0)
return;
// set capacity to obj.vSize. since we are building the vector,
// copy is false
reserve(obj.vSize, false);
// assign size to obj.vSize
vSize = obj.vSize;
// copy items from the obj.vArr to the newly allocated array
for (i = 0; i < vSize; i++)
vArr[i] = obj.vArr[i];
}
// destructor. deallocate the dynamic array
template <typename T>
miniVector<T>::~miniVector()
{
if (vArr != NULL)
// de-allocate memory for the array
delete [] vArr;
}
// replace existing object (left-hand operand) by
// rhs (right-hand operand)
template <typename T>
miniVector<T>& miniVector<T>::operator= (const miniVector<T>& rhs)
{
int i;
// check vCapacity to see if a new array must be allocated
if (vCapacity < rhs.vSize)
// make capacity of current object the size of rhs. don't
// do a copy, since we will replace the old values
reserve(rhs.vSize, false);
// assign current object to have same size as rhs
vSize = rhs.vSize;
// copy items from rhs.vArr to vArr
for (i = 0; i < vSize; i++)
vArr[i] = rhs.vArr[i];
return *this;
}
// check vSize and throw an underflowError exception if the
// value is 0; otherwise return the element vArr[vSize-1]
template <typename T>
T& miniVector<T>::back()
{
if (vSize == 0)
throw underflowError(
"miniVector back(): vector empty");
return vArr[vSize-1];
}
template <typename T>
const T& miniVector<T>::back() const
{
if (vSize == 0)
throw underflowError(
"miniVector back(): vector empty");
return vArr[vSize-1];
}
// provides general access to array elements
template <typename T>
T& miniVector<T>::operator[] (int i)
{
if (i < 0 || i >= vSize)
throw indexRangeError(
"miniVector: index range error", i, vSize);
return vArr[i];
}
// provides general access to array elements. constant version
template <typename T>
const T& miniVector<T>::operator[] (int i) const
{
if (i < 0 || i >= vSize)
throw indexRangeError(
"miniVector: index range error", i, vSize);
return vArr[i];
}
// insure that list has sufficient capacity,
// add the new item to the list, and increment vSize
template <typename T>
void miniVector<T>::push_back(const T& item)
{
// if space is full, allocate more capacity
if (vSize == vCapacity)
{
if (vCapacity == 0)
// if capacity is 0, set capacity to 1.
// set copy to false because there are
// no existing elements
reserve(1,false);
else
// double the capacity
reserve(2 * vCapacity, true);
}
// add item to the list, update vSize
vArr[vSize] = item;
vSize++;
}
// if not empty, just decrement the size
template <typename T>
void miniVector<T>::pop_back()
{
if (vSize == 0)
throw underflowError(
"miniVector pop_back(): vector is empty");
vSize--;
}
template <typename T>
int miniVector<T>::size() const
{
return vSize;
}
template <typename T>
bool miniVector<T>::empty() const
{
return vSize == 0;
}
template <typename T>
int miniVector<T>:: capacity() const
{
return vCapacity;
}
#endif // MINI_VECTORTop
2 楼mingpingzhang（张三）回复于 2005-04-02 09:36:23 得分 0
一定要这么麻烦吗，要自己写一个类，不能使用STL的vector或list构建一个吗？Top
3 楼pcboyxhy（-273.15℃）回复于 2005-04-02 09:41:52 得分 0
CustomerInfo.push_back( 这里是结构体变量 );Top
4 楼MadLee（风里麦笛）回复于 2005-04-02 09:43:16 得分 10
int main()
{
vector <Info> CustomerInfo;
Info v;
while(cin >> v.name >> v.age)
{
CustomerInfo.push_back(v);
}
for (int i = 0; i < CustomerInfo.size(); ++i)
{
cout << "Name: " << CustomerInfo[i].name << endl
<< "Age: " << CustomerInfo[i].age << endl;
}
}
Top
5 楼CloudOfFly（追忆）回复于 2005-04-02 10:11:48 得分 0
楼上的写法不错Top
6 楼oyljerry（【勇敢的心】→ ㊣提拉米苏√㊣）回复于 2005-04-02 12:28:25 得分 0
先填好结构体，然后插入Top
7 楼JustLikeTheWind（风）回复于 2005-04-02 12:54:50 得分 10
#include <cstdlib>
#include <ctime>
#include <iostream>
#include <algorithm>
#include <vector>
#include <boost/lambda/lambda.hpp>
using namespace std;
using namespace boost::lambda;
struct Info
{
Info(int nAge):age(nAge){}
Info(){}
int age;
};
ostream& operator<<(ostream& out, const Info& rhs){return out<<rhs.age;}
Info MyRnd(){return Info(rand()%100+1);}
int main()
{
srand( (int)time(0) );
vector<Info> vi(10);
generate(vi.begin(), vi.end(), &MyRnd);
for_each(vi.begin(), vi.end(), cout<<_1<<'\n');
cout<<endl;
system("pause");
return 0;
}Top
8 楼JustLikeTheWind（风）回复于 2005-04-02 13:01:13 得分 0
或者这样
int main()
{
vector <Info> CustomerInfo;
while(bHasCreatedEnoughInfo)
CustomerInfo.push_back(InfoFactory.newInstance());
for_each(CustomerInfo.begin(),CustomerInfo.end(),cout<<_1<<'\n');
system("pause");
return 0;
}Top
9 楼mingpingzhang（张三）回复于 2005-04-02 13:08:47 得分 0
非常感谢!Top
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