Question

我正在尝试将.txt文件读入此程序中的struct数组并显示内容该文件如下所示：

Smith   Jack    60    45    98  
Harry   Hisk    45    40    78  
Kay     Jacob   35.5  23    45  
Dos      hed    23    20    35  
Noa      Tom    55    12    32  
Joe      Peni   57    49    78  
Vin      San    25.6  23    65.5  
Jes      Dan    24.3  12    78  
Zi       Lee    56    49    99  
Angi     Dev    57    48    97  
Donald   David  60    50    96  
Davis    Lal    47    47    80  
Alvis   Sen     56    46    85  
Jack    Jill    45    45    75  
Messy   Lionel  60    49    100

我正在运行的代码：

#include <iostream>
#include <string>
#include <fstream>
using namespace std;
int main(){
    const int SIZE=50;
    int i;
    struct Records {
        string firstname;
        string secondname;
        float test1mark;
        float midtestmark;
        float annualmark;
    }record[SIZE];

    ifstream in("Data.txt");

    if (!in){
    cerr << "File can't be opened! " << endl;
    system("PAUSE");
    exit(1);
    }
    for (int i=0; i < SIZE; i++){
    in >> record[i].firstname >> record[i].secondname 
    >>record[i].test1mark >> record[i].midtestmark >> record[i].annualmark ;
    }
    for (int i=0;i< SIZE;i++) {
        cout << record[i].firstname<<"  ";
        cout << record[i].secondname<<" ";
        cout << record[i].test1mark<<"  ";
        cout << record[i].midtestmark << "  ";
        cout << record[i].annualmark << "   ";
    }   
return 0;
}

我得到的输出：

Smith   Jack    60      45      98  
Harry   Hisk    45      40      78  
Kay     Jacob   35.5    23      45  
Dos     hed     23      20      35    
Noa     Tom     55      12      32  
Joe     Peni    57      49      78  
Vin     San     25.6    23      65.5  
Jes     Dan     24.3    12      78  
Zi      Lee     56      49      99  
Angi    Dev     57      48      97  
Donald  David   60      50      96  
Davis   Lal     47      47      80  
Alvis   Sen     56      46      85  
Jack    Jill    45      45      75  
Messy   Lionel  60      49      100  
                nan     0       8.94237e-039  
                4.36192e-039    0       -2.3511e-038  
                0       0       -2.3511e-038  
                0       0       0  
                1.32253e-038    0       1.32251e-038  
                4.2039e-045     0       -2.11122e+037  
                1.32251e-038    0       3.21276e-039  
                1.4013e-045     0       -2.3511e-038  
                1.4013e-045     0       3.76158e-037  
                0       0       3.76158e-037  
                0       0       1.12104e-044  
                4.36195e-039    0       4.36194e-039  
                3.57331e-043    0       6.0615e-039  
                0       0       3.21276e-039  
                4.2039e-045     0       6.41272e-039  
                1.12104e-044    0       6.63812e-039  
                4.36205e-039    0       -2.75237e+038  
                0       0       6.59812e-039  
                6.63426e-039    0       1.4013e-045  
                0       0       6.47961e-039  
                3.21319e-039    0       3.21319e-039  
                6.59812e-039    0       3.21299e-039  
                8.40779e-045    2.24208e-044    6.01433e-039  
                6.6045e-039     0       2.54408e-029  
                0       0       6.6045e-039  
                0       0       6.43946e-039  
                5.88656e-039    0       -4.12495e+011  
                0       0       0
                5.88656e-039    0       2.54408e-029  
                nan     nan     6.43029e-039  
                0       0       0
                5.93823e-039    0       -4.12495e+011  
                0       0       0
                5.93823e-039    0       5.74532e-044  
                nan     nan     5.93837e-039

过程在0.05447秒后退出，返回值为0
按任意键继续。。。

有人可以告诉我它有什么问题吗？我尝试过使用指针，但情况变得更糟。 -Beginner

Answer 1

您的文件有15行，因此您只能读取15行数据。您正在使用变量SIZE来控制应读取的行数。

问题是SIZE是50！它是不 15。当您尝试读取文件末尾时，输入将不读取超过16 ^th行。因此，索引15之后的变量将是未初始化的，即未定义。

将文件中的行数增加到50，或将SIZE更改为15。

Answer 2

正如@ Rackete1111的另一个答案所述，您指定了太多项目，并且您的循环读取数据超过了文件中的实际项目数。

话虽如此，只要你正确地写出读取循环，就没有任何错误（除了浪费空间，如果你假设你的数组太大），夸大你有多少条记录。以下是编写循环的方法，即使你犯了＆＃34;错误＆＃34;陈述50项而不是15：

#include <iostream>
#include <string>
#include <iostream>

using namespace std;

int main(){
    const int SIZE=50;
    int i;
    struct Records {
        string firstname;
        string secondname;
        float test1mark;
        float midtestmark;
        float annualmark;
    };

    Records record[SIZE];

    ifstream in("Data.txt");

    int recCount = 0;  // keep track of actual number of records

    // loop until we reach the end of file, or until we hit SIZE records,
    // whichever comes first
    while (!in.eof() && recCount < SIZE)
    {
        in >> record[recCount].firstname >> record[recCount].secondname 
        >>record[recCount].test1mark >> record[recCount].midtestmark >> record[recCount].annualmark ;
        ++recCount;
    }

    // now recCount == 15 if you have 15 items.

Live Example

注意我们有一个while循环，直到达到限制（50），或者我们点击文件结尾。

Answer 3

而且我相信我们并不需要

int i;

开头

#include <iostream>
#include <string>
#include <fstream>
using namespace std;



ifstream in("Data.txt");
const int SIZE = 15;
void debugPrint();
void loadData();

struct Records {
    string firstname;
    string secondname;
    float test1mark;
    float midtestmark;
    float annualmark;   
}record[SIZE];

int main()
    {
    loadData();
    debugPrint();
    }

void debugPrint()
{
    for (int i = 0; i < SIZE; i++) 
    {
        cout << record[i].firstname << "  ";
        cout << record[i].secondname << " ";
        cout << record[i].test1mark << "  ";
        cout << record[i].midtestmark << "  ";
        cout << record[i].annualmark << "  " <<endl;        
    }
    system("PAUSE");
}

void loadData()
{   
    for (int i = 0; i < SIZE; i++)
    {
        if (!in)
        {                                               
            cerr << "File can't be opened! " << endl;
            system("PAUSE");
        }

        in >> record[i].firstname >> record[i].secondname
        >> record[i].test1mark >> record[i].midtestmark >> record[i].annualmark;
    }
}

将文件读入struct c ++数组

3 个答案: