Question

第二个if语句遇到问题只能读取十个值。如果我删除程序将编译。我需要它为我已经尝试过几次修改的作业，所以这里的内容可能无法反映我的最后一次尝试。用if语句编译C ++ homework编译错误。详细说明在发布之前我需要添加多少详细信息，更多详细信息

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

    /**********************************************************************
    * Get File
    * This function will prompt the user for the name of the file and
    * return it.
    *********************************************************************/

    void getFileName(char fileName[])
    {
        //prompt the user
        cout << "Please enter the filename: ";
        cin >> filename;

        ofstream fout(fileName);
    }

    /**********************************************************************
    * Read
    * This function will read the file and return the average score of the
    * ten values.
    *********************************************************************/

     float readFile(char fileName[])
     {
         cout.setf(ios::fixed);  //no scientific notation
         cout.precision(0);      //no decimals

         //In case of error
         ifstream fin(filename);
         if (fin.fail())
         {
             cout << "Error reading file \"" << fileName << "\"" << endl;
             exit(0);
         }

         float data;          //always need a variable to store the data
         float i = 0;         //don't forget to initialize the variable
         float gradeSum = 0;  
         float average;

         //Add up all the grades
         while (fin >> data)   //while there was not an error
         {
              gradeSum += data; //do the work
              i++;
         }

         // Hint: Make sure you only read ten values.
         if (i != 10)
         {
             //tell the user what happened
             cout < "Error reading file \"" << fileName << "\"" << endl;
             exit(0);
         }

         //Calculate average grade
         average = gradeSum / i;

         //Close file
         fin.close();

         return average;
     }

    /**********************************************************************
    * Display function
    * This function will display the average score to zero decimals of
    * accuracy.
    *********************************************************************/
    void display(float average)
    {
       cout << "Average Grade: " << average << "%" << endl; 
    }

    /**********************************************************************
    * main calls average grade and file name
    ***********************************************************************/
    int main()
    {
       char fileName[256];
       getFileName(fileName);

       int average = readFile(fileName);
       return 0;
    }

Answer 1

注意if语句相对于while循环的位置。你的if语句什么时候运行？你的while循环何时运行？

考虑到这些，你如何调整你的while循环以考虑你的限制（当i = 10时循环停止执行）？

我希望这可以帮助您更好地理解您需要做的事情，而不会破坏太多的答案。

P.S。如果i！= 10，那么if块的内容将在现场退出程序，而不执行任何操作。

if (i != 10)
     {
         //tell the user what happened
         cout < "Error reading file \"" << fileName << "\"" << endl;
         exit(0);
     }

Answer 2

关于流操作符的简单错误。

这一行：

cout < "Error reading file \"" << fileName << "\"" << endl;

应该是：

cout << "Error reading file \"" << fileName << "\"" << endl;

此外，您还有其他错别字来阻止您的代码编译：即整个filename和fileName的大小写混合使用情况。在我将这些变量namings一致地fileName修复后，它编译了。

Answer 3

您的cout无效。 cout << "Average Grade: " << average << "%" << endl;代替"cout < Average Grade: " << average << "%" << endl;

用if语句编译C ++ homework编译错误

3 个答案: