Question

我目前正在编写一个程序，该程序将在4列（ID，名字，姓氏和GPA）中显示学生记录，以升序对他们的记录进行排序，并将每个GPA重置为0.0排序的学生记录。

学生记录存储在一个名为“ StudentInfo.txt”的文本文件中

123456789   John    Johnson    3.5
512434990   Mary    Jackson    3.9
342432444   Peter   Young      2.3
470068625   Jim     Lee        2.9
234324324   Tammy   Gaddis     3.1
121219000   Ester   Schwab     2.7

我遇到的麻烦是在ifstream inputFile之前声明一个结构数组。在第42、53和68行显示错误消息"arrStud was not declared in this scope"。

我尝试实现studentInfo **arrStud[SIZE]和studentInfo *arrStud[SIZE]，但是它不起作用，并且发生了另一堆错误。

如果有人可以帮助我解决此问题，我将不胜感激！

我当前的代码：

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

using namespace std;

struct studentInfo
{
    int ID;
    string firstName;
    string lastName;
    double GPA;
};

const int SIZE = 100;
void display(/*parameter*/,int);
void resetGPA(studentInfo **, int);
void sortStud(studentInfo **, int);

int main()
{
    int counter = 0;
    int ID;
    string firstName;
    string lastName;
    double GPA;

    // Declare arrStud here...

    ifstream inputFile;

    inputFile.open("StudentInfo.txt");
    if (inputFile.is_open())
    {
        cout << "ID:" << setw(15) << "Name:" << setw(14) << "GPA:" << endl;
        cout << "-------------------------------------------" << endl;

        while(!inputFile.eof())
        {
            inputFile >> ID >> firstName >> lastName >> GPA;
            arrStud[counter] = new studentInfo;

            arrStud[counter]->ID = ID;
            arrStud[counter]->firstName = firstName;
            arrStud[counter]->lastName = lastName;
            arrStud[counter]->GPA = GPA;

            counter++;
        }

        for (int i = 0; i < counter; i++)
        cout << i << arrStud[i]->ID
             << setw(8) << arrStud[i]->firstName
             << setw(10) << arrStud[i]->lastName
             << setw(8) << arrStud[i]->GPA
             << endl;
        cout << "-------------------------------------------" << endl;
        cout << endl;

        inputFile.close();
    }
    else
        cout << "File cannot be opened.";
        inputFile.close();


    display(arrStud, counter);
    cout << endl;
    cout << "Sorting Students by ID..." << endl;
    cout << endl;
    sortStud(arrStud, ID);
    cout << endl;
    cout << "Resetting GPA Data..." << endl;
    cout << endl;
    resetGPA(arrStud, GPA);
}

void display()
{

}

void resetGPA(studentInfo** students, int numStu)
{

    for (int i = 0; i < numStu; i++)
    {
        students[i]->GPA = 0.0;
    }

}

void sortStud(studentInfo** students, int numStu)
{
    int lowestIDIndex; //holds the index in the array students of the student with the lowest ID

    for (int i = 0; i < numStu; i ++)
    {
        lowestIDIndex = i; //always start with lowest ID being first student

        for (int j = i; j < numStu; j++) //j is equal to i so that you don't search the already sorted elements, which are less than i
        {
            if (students[j]->ID < students[lowestIDIndex]->ID) //search for the lowest ID
            {
                lowestIDIndex = j; //keep track of the lowest ID
            }
        }
            //switch the lowest element with the front-most element
            studentInfo* tempStuPtr = students[i];
            students[i] = students[lowestIDIndex];
            students[lowestIDIndex] = tempStuPtr;
    }
}

预期输出：

ID:          Name:          GPA:
-----------------------------------
123456789    John   Johnson     3.5
512434990    Mary   Jackson     3.9
342432444   Peter     Young     2.3
470068625     Jim       Lee     2.9
234324324   Tammy    Gaddis     3.1
121219000   Ester    Schwab     2.7
-----------------------------------


Sorting Students by ID...

ID:          Name:          GPA:
-----------------------------------
512434990    Mary   Jackson     3.9
123456789    John   Johnson     3.5
234324324   Tammy    Gaddis     3.1
470068625     Jim       Lee     2.9
121219000   Ester    Schwab     2.7
342432444   Peter     Young     2.3
-----------------------------------


Resetting GPA Data...

ID:          Name:          GPA:
-----------------------------------
512434990    Mary   Jackson     0.0
123456789    John   Johnson     0.0
234324324   Tammy    Gaddis     0.0
470068625     Jim       Lee     0.0
121219000   Ester    Schwab     0.0
342432444   Peter     Young     0.0
-----------------------------------

Answer 1

您的代码中没有声明arrStud！您需要在main()函数顶部附近添加类似的内容（或将其作为全局变量，例如在main定义之前说）：

studentInfo* arrStd[SIZE];

然后，在main的结尾处（或附近），您需要释放通过new调用创建的内存：

for (int c = 0; c < counter; ++c) delete arrStud[c];

您还需要更正display函数的声明和定义，如下所示：

void display(studentInfo**, int);

void display(studentInfo** students, int numStu)
{
    // Do something here, I guess!
}

如何修复C ++中的'arrStud在此范围内未声明'错误

1 个答案: