當寫入文件時，只有最後一行保存到我的輸出文件

Question

我試圖寫入文件，但只有最後一行被寫入文件。我試過打開和關閉循環外的文件，但是沒有任何文件寫入文件

void getValues (double totalEnergy, double meanPowerConsumption, double maxPowerConsumption); 

int main() 
{ 
    double totalEnergy, meanPowerConsumption, maxPowerConsumption; 
    getValues(totalEnergy, meanPowerConsumption, maxPowerConsumption); 

    return 0; 
} 

void getValues(double totalEnergy, double meanPowerConsumption, double maxPowerConsumption) 
{ 
    int x = 0; 
    int c = 0; 
    double p = 0; 
    int i = 0; 
    ifstream inFile; 
    inFile.open("data.txt"); 

    if (inFile.fail()) 
    { cerr << "Error opening file." << endl; 
     exit(1); 
    } 

    // Declaring variables. 
    double power1, power2, time1, time2, totalPower, timeConstant, changeInPower, totalTime, time, coloumns; 
    double year, month, day, hour, minute, second, voltage, current, frequency; 
    double accumulatedPower=0; 

    while(!inFile.eof()) 
    { 
     inFile >> year >> month >> day >> hour >> minute >> second >> voltage >> current >> frequency; 

     //Should have taken into account 'Years','Months' and 'Days' but its throws the calculations into exponents. 
     time2 = ((3600*hour) + (minute *60) + second); 

     if (x==0) 
     { 
      timeConstant = 0; 
      time1 = 0; 
      totalTime = 0; 
     } 
     else 
     { 
      timeConstant = time2 - time1; 
      totalTime = totalTime + timeConstant; 
     } 

     //cout << "time1: " << time1 << endl; 
     //cout << "time2: " << time2 << endl; 
     //cout << "Time Constant: " << timeConstant<< endl; 
     //cout << "Total Time" << totalTime << endl; 

     power2 = voltage*current; 

     if (x==0) 
     { 
      power1 = 0; 
      changeInPower = 0; 
      totalPower = 0; 
      totalEnergy = 0; 
      meanPowerConsumption = 0; 
     } 
     else 
     { 
      changeInPower = (power1 + power2)/2; 
      totalPower = totalPower + changeInPower; 
     } 

     // cout << "Counter" << c << endl; 
     // Assumed that mean powerconsumption is the average of all powers entered. 
     meanPowerConsumption = totalPower/c; 

     // Testing Variables. 
     //cout << "power1: " << power1 << endl; 
     //cout << "power2: " << power2 << endl; 
     //cout << "Change in Power: " << changeInPower << endl; 
     //cout << "total Power: " << totalPower << endl; 


     //Numerical Integration: 
     totalEnergy = totalEnergy + (timeConstant*changeInPower); 

     //Counter Loop: 

     if (power2 > maxPowerConsumption) 
     { 
      maxPowerConsumption = power2; 
     } 


     accumulatedPower = accumulatedPower + power1; 
     time = time2 - time1; 
     p = p + time; 


     ofstream outFile; 
     outFile.open("byhour.txt"); 

     for (coloumns=0; p>=3599; coloumns++) 
     { 
      i++; 
      outFile << i << " " << accumulatedPower/3600000 << endl; 

      accumulatedPower=0; 
      p=0; 
     } 

     outFile.close(); 

     cout << "coloumns: " << i << endl; 
     cout << "P value " << p << endl; 
     cout << "accumulated power" << accumulatedPower << endl; 

     cout << "The total Energy is: " << totalEnergy/3600000 << "KwH" << endl; 
     cout << "The mean power consumption is: " << meanPowerConsumption << endl; 
     cout << "The Max Power Consumption is:" << maxPowerConsumption << endl; 
     cout << endl ; 

     c++; 
     x++; 

     time1 = time2; 
     power1 = power2; 
    } 

    ofstream outStats; 
    outStats.open("stats.txt"); 

    outStats << totalEnergy/3600000 << endl; 
    outStats << meanPowerConsumption << endl; 
    outStats << maxPowerConsumption << endl; 

    outStats.close(); 
} 

這就是完整的代碼。我試着拿出來放回去（打開和關閉文件）。目前爲止沒有任何工作

Answer 1

您正在打開和關閉循環中的文件;基於默認模式，它會打開文件中的第一個位置，因此每寫入一個文件，寫入文件的開頭（可能會覆蓋之前的文件），然後關閉它。

您應該打開一次文件，寫出一個循環，然後在循環外部關閉。

Answer 2

您的for循環實際上正在運行（至多）一次。

for (coloumns=0; p>=3599; coloumns++) 
{ 
    ... 
    p=0; 
} 

假設p至少3599在循環的開始，環路將僅運行一個單一的時間，因爲p得到在循環的結束設置爲0（意味着測試將是假的下一時間和循環停止）。

如果p在開始時小於3599，當然它根本不會運行。