我遇到了过去4小时内一直试图找到的细分错误。以下是valgrind可能使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();
}
}
以下是valgrind在
时提供的信息==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)
我有另一个学生班级已经完成并且经过测试才能正常工作，所以错误必须在课程中。
课程标题文件：
#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
学生班级定义：
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;
}
答案 0 :(得分：3)
您在几个地方都有未定义的行为。第一个是在Course构造函数中，您在其中写入enrolled 越界。第二种是当使用时使用该数组中的未初始化的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，请逐个初始化每个索引，或使用初始化列表将整个数组初始化为相同的值。