我对此计划有一些疑问。我首先快速解释它的作用。它从文件中读取名称和统计信息，如下所示：
1880 John 0.081541 boy
1880 William 0.080511 boy
1880 James 0.050057 boy
1880 Charles 0.045167 boy
1904 Zola 0.000157 girl
1904 Juana 0.000154 girl
1904 Ramona 0.000154 girl
1904 Carmella 0.00015 girl
我要阅读它并存储在动态数组中，并能够使用方法进行组织。我的问题是： 1）我的提取操作员有什么问题？为什么不能看到人员阵列？我应该在那里打开文件吗？ 2）为什么我的主要不能看到checkLines函数？我不认为它应该是一个成员函数，我认为它应该是独立的。 3）我的复制构造函数有什么问题？有一条黄线而不是红线，错误如下：
Multiple markers at this line
- Member 'capacity' was not initialized in this
constructor
- Member 'people' was not initialized in this
constructor
- Member 'fillCount' was not initialized in this
constructor
这是代码
BabyNames.h
#ifndef BABYNAMES_H_
#define BABYNAMES_H_
#include <string>
#include <fstream>
using namespace std;
/**
* gender: an enum to hold types boy and girl
*/
enum gender {boy, girl};
/**
* PeopleStats: a data struct to hold year, name, double, and the enum type
* gender
*/
struct PeopleStats {
short year;
string name;
double percent;
gender sex;
};
/**
* Names: A class that reads data from a file into a PeopleStats Array
* and is capable of sorting them by name and by popularity percentage
*/
class BabyNames {
public:
int checklines(const char fn[]);
BabyNames(BabyNames& people);
BabyNames(const char fn[], const int numLines);
~BabyNames();
gender parseSex(string s);
void swap(int i);
const int getCapacity();//getter for dataSize
const PeopleStats& get(int i) const; //getter for objects of the data array
void sortByName(); //Sorts the names alphabetically
void sortByPopularity();//Sorts the names by popularity
void sortByYear();
friend std::ostream& operator << (std::ostream& os, const PeopleStats& d);
friend std::ostream& operator << (std::ostream& os, const BabyNames& bn);
friend std::istream& operator >> (std::istream& in, PeopleStats& ac);
friend std::istream& operator >> (std::istream& in, BabyNames& ac);
//int filled; //keeps track of how many array locations have data objects
private:
static const int MAX_DATA_SIZE = 2000;
PeopleStats* people;
int capacity;
int fillCount; // to keep track of how many array locations have data objects in them
static const int OUT_OF_BOUNDS = -1;
};//end of class
#endif /* BABYNAMES_H */
BabyNames.cpp
#include <iostream>
#include <string>
#include <fstream>
using namespace std;
#include "BabyNames.h"
/**
* BabyNames: A class that reads data from a file into a PeopleStats Array
* and is capable of sorting them by name and by popularity percentage
*/
BabyNames::BabyNames(const char fn[], const int numLines) {
people = new PeopleStats[numLines];
capacity = numLines; //set current capacity
ifstream myfile; //Open File
myfile.open(fn); //read in data
int filled = 0;
while (filled < capacity) {
myfile >> people[filled].year;
myfile >> people[filled].name;
myfile >> people[filled].percent;
string sex;
myfile >> sex;
people[filled].sex = parseSex(sex);
filled++;
}
}
//Copy Constructor
BabyNames::BabyNames(BabyNames& people){
PeopleStats* copyPeople = new PeopleStats[];
for (int i=0; i<500 ;i++)
copyPeople[i] = people[i];
}
PeopleStats& operator =(const PeopleStats& people){
PeopleStats x = new PeopleStats[2000];
for (int i=0; i<2000 ;i++)
x[i] = people[i];
return *this;
}//make a member with one parameter
std::istream& operator >> (std::istream& in, PeopleStats& ac){
string str;
ifstream myfile; //Open File
myfile.open(fn); //read in data
int filled = 0;
myfile >> people[filled].year;
myfile >> people[filled].name;
myfile >> people[filled].percent;
string sex;
myfile >> sex;
people[filled].sex = parseSex(sex);
filled++;
}
}//struct doesnt need a loop in the operator
return in;
}
std::istream& operator >> (std::istream& in, BabyNames& ac){
string str;
while (in >> str){
string strInput;
getline(inf, strInput);
in >> strInput;
}//struct doesnt need a loop in the operator
return in;
}
//Baby names extraction operator does need a loop
int checkLines(const char fn[]){
int number_of_lines = 0;
std::string line;
ifstream myfile("textexample.txt");
while (std::getline(myfile, line))
++number_of_lines;
std::cout << "Number of lines in text file: " << number_of_lines;
return number_of_lines;
}//make a stand alone function
BabyNames::~BabyNames(){
cout << "Destructor to deallocate memory... Done!" << endl;
delete[]people;
}
/*
* sortByName - Sorts the entire array of people by name using the bubble
* sort algorithm. Array is sorted according to name, within the structure
* Algorithm becomes extremely slow if capacity > 3000
*/
void BabyNames::sortByName(){
//sorted is set to true if no changes were made
bool sorted = false;
//change tells the loop if we made a swap or not
bool change = false;
while (!sorted) {
for (int i = 0; i < capacity - 1; i++) {
int compare = people[i].name.compare(people[i + 1].name);
if (compare == 1) {
swap(i);
change = true;
}
}
//if the array was not changed,
//changed sorted to true and exit loop
if (change == false)
sorted = true;
//otherwise reset change and repeat the loop
else
change = false;
}
}
/**
* sortByPopularity - sorts the entire array using the bubble sort algorithm
* Method is almost exactly the same as sortByName, except the compare
* variable is a double consisting of the difference of the two popularity
* percentages.
* Algorithm becomes extremely slow if capacity > 3000
*/
void BabyNames::sortByPopularity(){
bool sorted = false;
bool change = false;
while (!sorted) {
for (int i = 0; i < capacity - 1; i++) {
double compare = people[i].percent - people[i + 1].percent;
if (compare < 0) {
swap(i);
change = true;
break;
}
}
if (change == false)
sorted = true;
change = false;
}
}
void BabyNames::sortByYear(){
bool sorted = false;
bool change = false;
while (!sorted) {
for (int i = 0; i < capacity - 1; i++) {
double compare = people[i].year - people[i + 1].year;
if (compare < 0) {
swap(i);
change = true;
break;
}
}
if (change == false)
sorted = true;
change = false;
}
}
/**
* swap - swaps the positions of people[i] and people[i + 1]
* @param i - index of the people array that will get swapped with i + 1
*/
void BabyNames::swap(int i) {
PeopleStats temp = people[i + 1];
people[i + 1] = people[i];
people[i] = temp;
}
/** string strInput;
getline(inf, strInput);
in >> strInput;
* parseSex: extracts the gender from the input and returns the appropriate enum
* @param s
* @return gender object
*/
gender BabyNames::parseSex(string s) {
if (s == "boy")
return boy;
else if (s == "girl")
return girl;
else
throw "invalid Gender";
}
/**
* getCapacity: returns the number of data entries stored.
* @return size of the data
*/
const int BabyNames::getCapacity(){
return capacity;
}
/**
* get: returns one PeopleStat Object
* @param i
* @require: i < capacity
* @return PeopleStat object
*/
const PeopleStats& BabyNames::get(int i) const {
if (i>=0 && i < capacity)
return people[i];
throw OUT_OF_BOUNDS;
}
/**
* << - overloads the outstream operator for PeopleStats object
* @param os
* @param d
* @return os : output stream
*/
std::ostream & operator << (std::ostream& os, const PeopleStats& d){
os << d.name << " " << d.year << " " << d.percent << " " << d.sex;
return os;
}
/**
* <<: overloads the outstream operator for the BabyNames object
* @param os
* @param bn
* @return
*/
std::ostream& operator << (std::ostream& os, const BabyNames& bn) {
os << " BabyNames object " << std::endl;
for (int i=0; i < 2000; i++ )
os << " " << (i+1) <<": " << bn.get( i ) << std::endl;
return os;
}//end of operator
主要
#include <iostream>
#include "BabyNames.h"
/**
* main: The client function that controls the server, BabyNames
* For reasons currently unknown, the program will take forever
* to run after the * 3000-5000 line mark.
* @return 0 if successful
*/
int main(void) {
/* cout << "People names: " << endl;
BabyNames names("src/people.txt", 2000);
cout << names;
cout << "Sorted by popularity" << endl;
names.sortByPopularity();
cout << names;
// cout << "Sorted by name" << endl;
// names.sortByName();
// cout << names;
cout << "Sorted by year" << endl;
names.sortByYear();
cout << names;
cout << "... done!" << endl;
return 0;*/
cout << "Baby names: " << endl;
const char filename[] = "src/people.txt";
cout << " 1. Reading file: \"" << filename << "\" ... ";
int number_of_names = checkLines(filename);
cout << " number of lines in file is: " << "2000";
BabyNames* names = new BabyNames( "src/people.txt", 2000 );
// read the contents of a file into names and print them
ifstream file( filename, ios::in );
file >> *names;
cout << " file has been read!" << endl;
// Sort and print
cout << " 2. Sorted by popularity:" << endl;
BabyNames* namesByPop = new BabyNames( *names );
namesByPop->sortByPopularity();
cout << *namesByPop;
// Sort and print
cout << " 3. Sorted by name:" << endl;
BabyNames* namesByName = new BabyNames( *names );
namesByName->sortByName();
cout << *namesByName;
// Sort and print
cout << " 4. Sorted by year:" << endl;
BabyNames* namesByYear = new BabyNames( *names );
namesByYear->sortByYear();
cout << *namesByYear;
cout << " 5. Original names:" << endl;
cout << *names;
delete names;
delete namesByYear;
delete namesByName;
delete namesByPop;
cout << "... all done!" << endl;
}
答案 0 :(得分：2)
1）因为您的提取运算符不是该类的成员。您需要ac.people。您应该在提取运算符中无法打开文件，打开的文件（或其他）通过in参数传入。
2）因为你没有告诉主要的（即你没有在主要人员可以看到的任何地方定义它）。也许最简单的方法是在BabyNames.h的底部附近添加int checkLines(const char fn[]);。
3）您的复制构造函数出错了。首先，它不会初始化您正在构造的对象，而只是创建一个名为copyPeople的数组，然后将其丢弃，您构建的对象完全不受影响。另一个问题是参数应该声明为const。像这样的东西会更好
//Copy Constructor
BabyNames::BabyNames(const BabyNames& bn){
people = new PeopleStats[bn.capacity];
for (int i=0; i<bn.capacity ;i++)
people[i] = bn.people[i];
capacity = bn.capacity;
fillCount = bn.fillCount;
}
由于类似的原因，您的赋值运算符也是错误的。