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我正在通过Accelerated C++的方式工作，并决定解决那里定义的结构之一。虽然这样做，但我遇到了一个问题：创建这些结构的向量并修改每个结构中的元素似乎都会修改其中的所有元素。我知道这可能意味着我已经将向量中的所有结构初始化为单个内存地址处的结构，但我使用.push_back（）方法将“虚拟”结构插入到向量中。我的印象是.push_back（）推入了它的参数副本，有效地创建了一个新的结构体。C++：为什么我的向量结构作为一个结构？
下面是结构的标题：
#ifndef _STUDENT_INFO__CHAPTER_9_H
#define _STUDENT_INFO__CHAPTER_9_H
#include <string>
#include <iostream>
#include <vector>
class Student_info9{
public:
Student_info9(){homework = new std::vector<double>;};
Student_info9(std::istream& is);
std::string getName() const {return name;};
double getMidterm() const {return midterm;};
double getFinal() const {return final;};
char getPassFail() const {return passFail;};
std::vector<double> *getHw(){return homework;};
void setName(std::string n) {name = n;};
void setMidterm(double m) {midterm = m;};
void setFinal(double f) {final = f;};
private:
std::string name;
double midterm;
double final;
char passFail;
std::vector<double> *homework;
};
#endif /* _STUDENT_INFO__CHAPTER_9_H */
这里是我与（原谅过度print语句打打闹闹的代码......一段时间尝试调试结果:) ）：
vector<Student_info9> did9, didnt9;
bool did_all_hw9(Student_info9& s)
{
vector<double>::const_iterator beginCpy = s.getHw()->begin();
vector<double>::const_iterator endCpy = s.getHw()->end();
return(find(beginCpy, endCpy, 0) == s.getHw()->end());
}
void fill_did_and_didnt9(vector<Student_info9> allRecords)
{
vector<Student_info9>::iterator firstDidnt = partition(allRecords.begin(), allRecords.end(), did_all_hw9);
vector<Student_info9> didcpy(allRecords.begin(), firstDidnt);
did9 = didcpy;
vector<Student_info9> didntcpy(firstDidnt, allRecords.end());
didnt9 = didntcpy;
}
int main(int argc, char** argv) {
vector<Student_info9> students;
Student_info9 record;
for(int i = 0; i < 5; i++)
{
students.push_back(record);
}
for(int i = 0; i < students.size(); i++)
{
students[i].setMidterm(85);
students[i].setFinal(90);
students[i].getHw()->push_back(90);
std::cout << "student[" << i << "]'s homework vector size is " << students[i].getHw()->size() << std::endl;
students[i].getHw()->push_back(80);
std::cout << "student[" << i << "]'s homework vector size is " << students[i].getHw()->size() << std::endl;
students[i].getHw()->push_back(70);
std::cout << "student[" << i << "]'s homework vector size is " << students[i].getHw()->size() << std::endl;
std::cout << "Just pushed back students[" << i << "]'s homework grades" << std::endl;
if(i == 3)
students[i].getHw()->push_back(0);
}
std::cout << "student[3]'s homework vector size is " << students[3].getHw()->size() << std::endl;
for(vector<double>::const_iterator it = students[3].getHw()->begin(); it != students[3].getHw()->end(); it++)
std::cout << *it << " ";
std::cout << std::endl;
std::cout << "students[3] has " << ((find(students[3].getHw()->begin(),students[3].getHw()->end(), 0) != students[3].getHw()->end()) ? "atleast one " : "no ")
<< "homework with a grade of 0" << std::endl;
fill_did_and_didnt9(students);
std::cout << "did9's size is: " << did9.size() << std::endl;
std::cout << "didnt9's size is: " << didnt9.size() << std::endl;
}
正如你可以打印报表看，似乎功课成绩被添加到只有一个Student_info9对象，其副本似乎填充整个矢量。我的印象是，如果您要在单个对象上使用连续的.push_back（）副本，则会创建该对象的副本，每个副本具有不同的内存地址。
我不确定这是否是问题的根源，但希望有人能指出我正确的方向。
谢谢。
顺便说一下，这些标头警卫[非法]（http：// stackoverflow。COM /问题/ 228783 /什么，是最规则有关，使用安下划线-IN-A-C-标识符）。 – GManNickG 2011-01-20 17:48:47