Question

我正在创建一个程序，它将从文件中读取并在屏幕和文件中输出数据。我在添加总体平均值和总计数之前就已经工作了，但现在它只是崩溃而在编译过程中没有错误。

我搜索了类似的主题，但无法找到任何有助于我修复这些错误的内容。任何帮助表示赞赏。

编辑：更新了代码，其中包含一些建议的更改。现在只是崩溃没有错误。

                          #include <iostream>
            #include <string>
            #include <limits>
            #include <cmath>
            #include <iomanip>
            #include <fstream>

            using namespace std;

            void gradeCalc(int studentID, int count, double midterm, double finalExam, double researchPaper, double groupProject, double participation, double studentAvg, double& overallAvg, double gradeSum);
            void printGrade(int studentID, int count, double midterm, double finalExam, double researchPaper, double groupProject, double participation, double studentAvg, double& overallAvg, double gradeSum);

            int main()
            {
                int studentID;
                int count = 0;

                double midterm;
                double finalExam;
                double researchPaper;
                double groupProject;
                double participation;
                double studentAvg;
                double overallAvg;
                double gradeSum;

                gradeCalc(studentID, count, midterm, finalExam, researchPaper, groupProject, participation, studentAvg, overallAvg, gradeSum);
                printGrade(studentID, count, midterm, finalExam, researchPaper, groupProject, participation, studentAvg, overallAvg, gradeSum);

                return 0;
            }

            void printGrade(int studentID, int count, double midterm, double finalExam, double researchPaper, double groupProject, double participation, double studentAvg, double& overallAvg, double gradeSum)
            {

                ifstream infile;
                ofstream outfile;

                infile.open("grades.dat");
                outfile.open("grades.txt");
                outfile << "STUDENT GRADING REPORT: ";
                outfile << fixed << showpoint << setprecision(2);

                while (!infile.eof()) {

                    infile >> studentID >> midterm >> finalExam >> researchPaper >> groupProject >> participation;

                    if (studentID > 1 && studentID <= 999) {

                        outfile << endl
                                << "Student ID: " << studentID << ' ' << "Midterm: " << midterm << ' ' << "Final Exam: " << finalExam << ' ' << "Research Paper: " << researchPaper << ' ' << "Group Project: " << groupProject
                                << "Participation: " << participation << ' ' << "Student Average: " << studentAvg;
                    }
                    overallAvg = gradeSum / count;
                    outfile << endl
                            << "Total # of Students: " << count
                            << "Overall Class Average: " << overallAvg;
                }

                infile.close();
                outfile.close();
            };

            void gradeCalc(int studentID, int count, double midterm, double finalExam, double researchPaper, double groupProject, double participation, double studentAvg, double& overallAvg, double gradeSum)
            {

                //midterm = .25
                //finalExam = .25
                //researchPaper = .20
                //groupProject = .20
                //participation = .10

                ifstream infile;
                ofstream outfile;

                infile.open("grades.dat");

                while (!infile.eof()) {

                    infile >> studentID >> midterm >> finalExam >> researchPaper >> groupProject >> participation;
                    studentAvg = ((midterm * .25) + (finalExam * .25) + (researchPaper * .20) + (groupProject * .20) + (participation * .10));
                    overallAvg = gradeSum / count;

                    if (studentID > 1 && studentID <= 999) {
                        count++;
                        gradeSum += studentAvg;

                        cout << endl
                             << fixed << showpoint << setprecision(2) << "Student ID: " << studentID << ' ' << "Average:  " << studentAvg;
                    }
                    cout << endl
                         << "Total # of Students: " << count
                         << "Overall Class Average: " << overallAvg;
                }

                infile.close();
            };

Answer 1

您需要解决一些语法问题：

printGrade()：

    outfile << endl
            << "Total # of Students: " << count; //<-- bad semicolon
    << "Overall Class Average: " << overallAvg;

gradeCalc()：

    cout << endl
            << "Total # of Students: " << count; //<-- bad semicolon
    << "Overall Class Average: " << overallAvg;

Answer 2

printGrade以overallAvg为参数。但它从不使用参数，而是将变量重新分配给：

overallAvg = gradeSum / count;

gradeCalc()有同样的问题。实际上，这些函数似乎都做了所有相同的计算。

您还使用未初始化的变量调用函数。

如果overallAvg应该是输出参数，则需要将其作为参考参数。

void printGrade(int studentID, int count, double midterm, double finalExam, double researchPaper, double groupProject, double participation, double studentAvg, double &overallAvg, double gradeSum)

表达式错误是由于这些行：

                cout << endl
                     << "Total # of Students: " << count;
                << "Overall Class Average: " << overallAvg;

第二行末尾的分号结束cout，因此第三行以无效运算符开头。摆脱那个分号。

                cout << endl
                     << "Total # of Students: " << count
                     << "Overall Class Average: " << overallAvg;

这也可能会修复有关未使用变量的警告，因为您在此输出语句中使用了该变量。

Answer 3

这取决于编译器。使用-Wno-unused-parameter标志进行编译。应该这样做。

参数未在函数C ++中使用

3 个答案: