在过去的 4 小时里，我一直试图找出一个段错误。以下是 valgrind 可能有用的代码和一些信息。
Course::Course()
{
courseid = "None";
courseName = "None";
enrolled[2] = {0};
}
Course::Course(string courseNum, string coursename, string filename)
{
courseid = courseNum;
courseName = coursename;
enrolled[2] = {0};
readStudentData(filename);
sortRow(0);
sortRow(1);
sortRow(2);
}
void Course::readStudentData(string filename)
{
std::ifstream inFile; //declare file input stream object
string first, last, zid;
int section;
inFile.open(filename.c_str()); //open file
if (!inFile)
{
cout << "File did not open successfully!"; //error checking
exit(EXIT_FAILURE);
}
inFile >> first; //read first
while (inFile)
{
inFile >> last;
inFile >> zid;
inFile >> section;
section--; //match section with array subscript
Student newStudent(last, first, zid); //fill contents read to new student object
Students[section][enrolled[section]] = newStudent; //fill Students array with new student
enrolled[section]++; //add the student to the enrolled counter
inFile >> first;
}
inFile.close();
}
void Course::sortRow(int RowtoSort)
{
int i, j;
Student bucket;
for(i = 1; i < enrolled[RowtoSort];i++)
{
bucket = Students[RowtoSort][i]; //assign bucket with temp value for swap
for(j = i; (j > 0) && (Students[RowtoSort][j-1].getLastName().compare(bucket.getLastName())) < 0; j--)
{
Students[RowtoSort][j] = Students[RowtoSort][j-1]; //assign j to element j-1 so now both j and j-1 are the same in the array
}
Students[RowtoSort][j] = bucket; //now j-1 value is at j and since j-- assign it to bucket to place the proper value at j-1
} // end outer loop
}
void Course::print()
{
cout << courseid << " " << courseName << endl; //header
cout << "Section 1" << endl; //print section 1
cout << left << "Name" << setw(40) << "Z-id" << endl;
for(int i=0;i<enrolled[0];i++)
{
Students[0][i].print();
}
cout << "Section 2" << endl; //print section 2
cout << left << "Name" << setw(40) << "Z-id" << endl;
for(int i=0;i<enrolled[0];i++)
{
Students[1][i].print();
}
cout << "Section 3" << endl; //print section 3
cout << left << "Name" << setw(40) << "Z-id" << endl;
for(int i=0;i<enrolled[0];i++)
{
Students[2][i].print();
}
}
这是valgrind给出的信息
==4223== Use of uninitialised value of size 8
==4223== at 0x4EF15F1: std::string::assign(std::string const&) (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.17)
==4223== by 0x4023E6: Student::operator=(Student const&) (in /home/ruslan/241Assign3/assign3)
==4223== by 0x401B9F: Course::readStudentData(std::string) (in /home/ruslan/241Assign3/assign3)
==4223== by 0x401836: Course::Course(std::string, std::string, std::string) (in /home/ruslan/241Assign3/assign3)
==4223== by 0x4012F9: main (assign3.cpp:27)
==4223==
==4223== Use of uninitialised value of size 8
==4223== at 0x4EF15F1: std::string::assign(std::string const&) (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.17)
==4223== by 0x402401: Student::operator=(Student const&) (in /home/ruslan/241Assign3/assign3)
==4223== by 0x401B9F: Course::readStudentData(std::string) (in /home/ruslan/241Assign3/assign3)
==4223== by 0x401836: Course::Course(std::string, std::string, std::string) (in /home/ruslan/241Assign3/assign3)
==4223== by 0x4012F9: main (assign3.cpp:27)
==4223==
==4223== Use of uninitialised value of size 8
==4223== at 0x4EF15F1: std::string::assign(std::string const&) (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.17)
==4223== by 0x40241C: Student::operator=(Student const&) (in /home/ruslan/241Assign3/assign3)
==4223== by 0x401B9F: Course::readStudentData(std::string) (in /home/ruslan/241Assign3/assign3)
==4223== by 0x401836: Course::Course(std::string, std::string, std::string) (in /home/ruslan/241Assign3/assign3)
==4223== by 0x4012F9: main (assign3.cpp:27)
==4223==
==4223== Invalid read of size 8
==4223== at 0x4EF15F1: std::string::assign(std::string const&) (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.17)
==4223== by 0x4023E6: Student::operator=(Student const&) (in /home/ruslan/241Assign3/assign3)
==4223== by 0x401B9F: Course::readStudentData(std::string) (in /home/ruslan/241Assign3/assign3)
==4223== by 0x401836: Course::Course(std::string, std::string, std::string) (in /home/ruslan/241Assign3/assign3)
==4223== by 0x4012F9: main (assign3.cpp:27)
==4223== Address 0x8050190f0 is not stack'd, malloc'd or (recently) free'd
==4223==
==4223==
==4223== Process terminating with default action of signal 11 (SIGSEGV)
==4223== Access not within mapped region at address 0x8050190F0
==4223== at 0x4EF15F1: std::string::assign(std::string const&) (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.17)
==4223== by 0x4023E6: Student::operator=(Student const&) (in /home/ruslan/241Assign3/assign3)
==4223== by 0x401B9F: Course::readStudentData(std::string) (in /home/ruslan/241Assign3/assign3)
==4223== by 0x401836: Course::Course(std::string, std::string, std::string) (in /home/ruslan/241Assign3/assign3)
==4223== by 0x4012F9: main (assign3.cpp:27)
我有另一个学生类(class)，该类(class)已被遵守并经过测试可以正常工作，所以错误一定在类(class)中。
类(class)头文件:
#ifndef COURSE_H
#define COURSE_H
#include "student.h"
using std::string;
class Course
{
private:
string courseid;
string courseName;
Student Students[3][45];
int enrolled[2];
public:
Course(); //default constructor
Course(string, string, string); //alternate constructor
void readStudentData(string);
void sortRow(int);
void print();
};
#endif //COURSE.H
学生类(class)定义:
Student::Student()
{
firstName = "None";
lastName = "None";
zid = "None";
}
Student::Student(string assignFirst, string assignLast, string assignZID)
{
firstName = assignFirst;
lastName = assignLast;
zid = assignZID;
}
string Student::getLastName()
{
return lastName;
}
void Student::print()
{
cout << lastName << ", " << firstName << std::setw(15) << zid << endl;
}
最佳答案
你在几个地方有未定义的行为。第一个是在 Course 构造函数中，您可以在其中写入 enrolled out of bounds。第二种是使用该数组中的未初始化值作为另一个数组的索引。
如果要在构造函数中初始化整个数组，要么将每个索引逐一初始化，要么使用初始化列表将整个数组初始化为相同的值。
关于c++ - 类定义中的段错误无法找出位置，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/19309093/