Question

我是一名非常新手的程序员，我正在尝试制作一个程序，该程序读取包含5名学生（仅限名字）姓名的txt文件以及每位学生的4个考试成绩。我尝试将名称读入名为students的数组中，然后将分数读入4个名为test1，test2，test3，test4的独立数组中，然后从监视器中显示。该文件如下所示：

  史蒂夫78 65 82 73

Shawn 87 90 79 82

Annie 92 90 89 96

Carol 72 65 65 60

凯西34 50 45 20

我很难分解阵列并组织它们。有人能帮我吗？请记住我非常新手，所以我不太了解编程。

到目前为止，这是我的代码：

#include <cstdlib>
#include <iostream>
#include <string>
#include <fstream>
#include <iomanip>
#include <ctime>
#define over2 "\t\t"
#define over3 "\t\t\t"
#define over4 "\t\t\t\t"
#define down5 "\n\n\n\n\n"


using namespace std;



int main(int argc, char *argv[])
{


    ifstream inputFile;


    //Constant for max string size
    const int SIZE = 5;


    //Constant for the scores
    string names[SIZE], fileName, line, test1[SIZE], test2[SIZE], test3[SIZE], test4[SIZE];


    //input section, user enters their file name
    cout << down5 << down5 << over2 << "Please enter your file name: ";
    cin >> fileName;
    system("CLS");




    //open the file containing the responses
    inputFile.open(fileName.c_str());
     cout << endl;

    //kicks you out if file isn't found
    if (inputFile)
    {
        for(int i = 0; i < SIZE; i++)
        {  
           getline(inputFile, line);
            names[i] = line;
            getline(inputFile, line);
            test1[i] = line;
            getline(inputFile, line);
            test2[i] = line;
            getline(inputFile, line);
            test3[i] = line;
            getline(inputFile, line);
            test4[i] = line;
        }   
            inputFile.close();  
    }
    cout << down5 << over3 << "Student\tTest1\tTest2\tTest3\tTest4\n";
    cout << over3 << "-------\t-----\t-----\t-----\t-----\n";   
    for(int i = 0; i < SIZE; i++)
    {
        cout << over3 << names[i] << endl;
        cout << over3 << test1[i] << endl;
        cout << over3 << test2[i] << endl;
        cout << over3 << test3[i] << endl;
        cout << over3 << test4[i] << endl;

    }
    return 0;
}

Answer 1

让我们看看你想要阅读的文件的结构：

Steve 78 65 82 73
Shawn 87 90 79 82
Annie 92 90 89 96
Carol 72 65 65 60
Kathy 34 50 45 20

数据的格式可以描述如下：

每一行代表一条“记录”。
每个“记录”包含多个列。
列由空格分隔。

您目前正在为每个列使用getline()：

for(int i = 0; i < SIZE; i++)
{  
  getline(inputFile, line);
  names[i] = line;
  getline(inputFile, line);
  test1[i] = line;
  getline(inputFile, line);
  test2[i] = line;
  getline(inputFile, line);
  test3[i] = line;
  getline(inputFile, line);
  test4[i] = line;
}

...而您实际上想要为每个记录单行阅读并将其拆分：

for (int i = 0; i < SIZE; i++)
{
  string line;
  size_t start = 0;
  // For each line, attempt to read 5 columns:
  getline(inputFile, line);
  names[i] = get_column(line, start);
  test1[i] = get_column(line, start);
  test2[i] = get_column(line, start);
  test3[i] = get_column(line, start);
  test4[i] = get_column(line, start);
}

以下是原始代码的修改版本，如上所述将每行分开：

#include <cctype>
#include <fstream>
#include <iostream>
#include <string>

using namespace std;

static string get_column(string line, size_t &pos)
{
  size_t len = 0;
  // Skip any leading whitespace characters.
  while (isspace(line.c_str()[pos])) { ++pos; }
  // Count the number of non-whitespace characters that follow.
  while (!isspace(line.c_str()[pos+len]) && line.c_str()[pos+len]) { ++len; }
  // Extract those characters as a new string.
  string result = line.substr(pos, len);
  // Update the "start" position (for the next time this function is called).
  pos += len;
  // Return the string.
  return result;
}

int main()
{

  const int SIZE = 5;
  string names[SIZE], test1[SIZE], test2[SIZE], test3[SIZE], test4[SIZE];

  // Ask the user to enter a file name.
  cout << "Please enter your file name: ";
  string fileName;
  cin >> fileName;

  // Open the file and read the data.
  ifstream inputFile(fileName.c_str());
  if (!inputFile.is_open()) { return 0; }

  for (int i = 0; i < SIZE; i++)
  {
    string line;
    size_t start = 0;
    // For each line, attempt to read 5 columns:
    getline(inputFile, line);
    names[i] = get_column(line, start);
    test1[i] = get_column(line, start);
    test2[i] = get_column(line, start);
    test3[i] = get_column(line, start);
    test4[i] = get_column(line, start);
  }

  inputFile.close();

  // Display the data.
  cout << "Student\tTest1\tTest2\tTest3\tTest4" << endl;
  cout << "-------\t-----\t-----\t-----\t-----" << endl;

  for(int i = 0; i < SIZE; i++)
  {
    cout << names[i] << "\t";
    cout << test1[i] << "\t";
    cout << test2[i] << "\t";
    cout << test3[i] << "\t";
    cout << test4[i] << endl;
  }

}

运行程序会产生以下输出：

Please enter your file name: textfile.txt
Student Test1 Test2 Test3 Test4
------- ----- ----- ----- -----
Steve   78    65    82    73
Shawn   87    90    79    82
Annie   92    90    89    96
Carol   72    65    65    60
Kathy   34    50    45    20

请注意，get_column()函数处理多个空格或太短的行，以便此文件：

Steve 78     65 82 73
Shawn   87 90 
Annie 92 90 89 96
Carol 72 
Kathy 34 50   45 20

...产生以下输出：

Please enter your file name: textfile.txt
Student Test1 Test2 Test3 Test4
------- ----- ----- ----- -----
Steve   78    65    82    73
Shawn   87    90
Annie   92    90    89    96
Carol   72
Kathy   34    50    45    20

Answer 2

之前的回答是过度思考问题。

您可以使用输入文件流来检索“格式化输入”（也就是说，您知道输入的格式为'string'，然后是'int'，'int'，'int'，'int'）使用＆gt;＆gt;操作

string name;

int score[4];

ifstream mf;

mf.open("score.txt");

// Get name string.
mf >> name;

// Get four score values into an array.
mf >> score[0] >> score[1] >> score[2] >> score[3];

然后：

cout << name;

cout << score[0];
cout << score[1];
cout << score[2];
cout << score[3];

从txt文件中分离并行数组

2 个答案: