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这是一个家庭作业。我遇到了一个奇怪的错误,我不知道是什么原因造成的。这不是全部任务,但它是我目前为止的任务。由于这是家庭作业,我不希望有人确切地告诉我如何编码,而是想知道是什么导致了我的崩溃以及我如何能够开始寻找如何解决它。一旦我的程序在 main 方法中遇到 return 语句,它似乎就崩溃了。所有输出似乎正是我想要获得的,并且我的文件被读取得很好。在打印完所有信息后按 Enter 键后,我会看到一个消息框,上面写着“Exams.exe 中 0x5286ad84 (msvcp100d.dll) 处的未处理异常:0xC0000005:访问冲突写入位置 0x00000063。” 感谢任何人都可以提供的任何帮助。

#include <stdio.h>
#include <string>
#define MAX_STUDENTS 100
#define MAX_QUESTIONS 50
using namespace std;

int fGetAnswers(FILE *p_inputf, int p_studentIds[], string p_studentAnswers[]);
int fGetAnswers(int p_studentIds[], string p_studentAnswers[]);
void printData(int numOfStudents, int numOfQuestions, string *p_correctAnswers, int studentIds[], string studentAnswers[]);

int main(void)
{
    // Declarations
    FILE *inputf = fopen("examdat.txt", "r"); // Opens "examdat.txt" and creates a pointer to it.
    int studentIds[MAX_STUDENTS];
    int *p_ids = studentIds; // Pointer to the studentIds array to pass to functions for manipulation.
    string studentAnswers[MAX_QUESTIONS];
    string *p_answers = studentAnswers; // Pointer to the studentAnswers array to pass to functions for manipulation.
    int numOfQuestions;
    string correctAnswers;
    int numOfStudents;
    fscanf(inputf, "%d %s", &numOfQuestions, correctAnswers); // Fetches the first line from the exam.dat file which contains the number of questions and the correct answers.

    int readFrom = 0;
    while (readFrom != 1 && readFrom != 2) // Loops until proper input is received. Asks if the user wants to read student data from the text file or enter it manually.
    {
        printf("1. Read student data from file.\n");
        printf("2. Enter student data manually.\n\n");
        printf("Please make a selection> ");
        scanf("%d", &readFrom);
        if (readFrom != 1 && readFrom != 2)
            printf("\nInvalid entry!\n");
    }
    if (readFrom == 1) // Calls fGetAnswers to retrieve answers from the text file.
        numOfStudents = fGetAnswers(inputf, p_ids, p_answers);
    else // Calls fGetAnswers to retrieve answers from the user via the keyboard.
        numOfStudents = fGetAnswers(p_ids, p_answers);

    fclose(inputf);

    printData(numOfStudents, numOfQuestions, &correctAnswers, studentIds, studentAnswers);

    getchar();
    getchar();
    return(0);
}
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2 回答 2

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可能有很多错误,使用调试器将帮助您跟踪它们。但我发现的两个是

printf("%d\t%s\n", numOfQuestions, *p_correctAnswers);

您不能将 C++ 字符串与 printf 一起使用,只能使用 C 字符串。这将起作用

printf("%d\t%s\n", numOfQuestions, p_correctAnswers->c_str());

c_str 方法从 C++ 样式字符串返回 C 样式字符串。

还有另一个类似的错误

int result = fscanf(p_inputf, "%d %s", &p_studentIds[i], p_studentAnswers[i]);

您不能将 C++ 字符串与 fscanf 一起使用。这个很难解决。由于您想使用 C++ 字符串(这是一个聪明的举动),我认为您还应该学习一些 C++ I/O,请查看iostreams

于 2013-10-13T09:42:34.697 回答
0

由于您使用的是 C++ 编译器,因此您可以消除一些 C 习惯(越早越好!)

#include <iostream> // for std::cout and std::cin

using namespace std::cin; 
using namespace std::cout;
using namespace std::endl;

而不是 printf (以及 john 指出的关于 C 样式字符串的问题),使用:

cout << numOfQuestions << "\t" << correctAnswers << endl;

您可以在此处阅读有关 cout的信息

于 2013-10-13T09:48:55.077 回答